https://wiki.jlab.org/ciswiki/api.php?action=feedcontributions&user=Chgarcia&feedformat=atomCiswikidb - User contributions [en]2024-03-19T10:06:39ZUser contributionsMediaWiki 1.35.7https://wiki.jlab.org/ciswiki/index.php?title=Mar_6_2024&diff=30714Mar 6 20242024-03-05T15:58:44Z<p>Chgarcia: </p>
<hr />
<div>==Updates==<br />
<br />
* Max, Gabriel<br />
** Repeated lens optimization for MFX2I01 and MFX1I03 to minimize beam size at MDR1I02 and MWF1I04...<br />
*** R30 16°/30°, SW FX lenses<br />
*** recess +0.1 mm, +0 mm, and -0.1 mm compared to nominal<br />
*** produced lens settings at 0.001 pC and used them at 0.340 pC (similar to machine setup strategy)<br />
*** [[media:Optimized lenses recess comparison.pdf|Comparison of R30 16°/30° lens optimization results]]<br />
*** qualitative shape of curves similar; doing the optimization the other way around would not change the numbers by too much<br />
*** recess affects optimal lens setpoints (unsurprisingly) but causes no unmanageable differences in beam parameters<br />
*** minor emittance increase due to space charge<br />
** Plan B<br />
*** we decided to keep the Plan A Pierce angle but use the junction design from R30-3<br />
*** mitigate risk of field enhancement at junction at the cost of higher surface field on lip<br />
*** Gabriel's material from last time for reference: [[media:R30-4_Junction_angle.pptx|R30-4 junction angle and lip radius gradients vs junction angle]]<br />
*** minor effect on beam: [[media:R30_16_30vs60.pdf|Comparison of R30 16°/30° and 16°/60° focal lengths]]<br />
** Test plan for R28 phase space measurement at CEBAF: https://tasklists.jlab.org/bslist/tasks/111123<br />
*** extends Yan's measurement with option for Twiss-parameter fit<br />
*** perfunctory attempt with R30-3 gun last summer gave excessive emittance, likely due to chromox viewer, but better than nothing?<br />
** Alicia<br />
*** [[media:Comparison_R282_140kV180kVops_settings_scaled_to_200kV_R304_16degPierce30degJunction_beamline_sims_20240303.pdf|140 and 180 kV R28-2 operational settings scaled to 200 kV for R30-4]]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=File:Comparison_R282_140kV180kVops_settings_scaled_to_200kV_R304_16degPierce30degJunction_beamline_sims_20240303.pdf&diff=30713File:Comparison R282 140kV180kVops settings scaled to 200kV R304 16degPierce30degJunction beamline sims 20240303.pdf2024-03-05T15:58:30Z<p>Chgarcia: </p>
<hr />
<div></div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Mar_6_2024&diff=30712Mar 6 20242024-03-05T15:57:49Z<p>Chgarcia: /* Updates */</p>
<hr />
<div>== Updates ==<br />
<br />
* Max, Gabriel<br />
** Repeated lens optimization for MFX2I01 and MFX1I03 to minimize beam size at MDR1I02 and MWF1I04...<br />
*** R30 16°/30°, SW FX lenses<br />
*** recess +0.1 mm, +0 mm, and -0.1 mm compared to nominal<br />
*** produced lens settings at 0.001 pC and used them at 0.340 pC (similar to machine setup strategy)<br />
*** [[media:Optimized lenses recess comparison.pdf|Comparison of R30 16°/30° lens optimization results]]<br />
*** qualitative shape of curves similar; doing the optimization the other way around would not change the numbers by too much<br />
*** recess affects optimal lens setpoints (unsurprisingly) but causes no unmanageable differences in beam parameters<br />
*** minor emittance increase due to space charge<br />
** Plan B<br />
*** we decided to keep the Plan A Pierce angle but use the junction design from R30-3<br />
*** mitigate risk of field enhancement at junction at the cost of higher surface field on lip<br />
*** Gabriel's material from last time for reference: [[media:R30-4_Junction_angle.pptx|R30-4 junction angle and lip radius gradients vs junction angle]]<br />
*** minor effect on beam: [[media:R30_16_30vs60.pdf|Comparison of R30 16°/30° and 16°/60° focal lengths]]<br />
** Test plan for R28 phase space measurement at CEBAF: https://tasklists.jlab.org/bslist/tasks/111123<br />
*** extends Yan's measurement with option for Twiss-parameter fit<br />
*** perfunctory attempt with R30-3 gun last summer gave excessive emittance, likely due to chromox viewer, but better than nothing?<br />
* Alicia<br />
** [[media:Comparison_R282_140kV180kVops_settings_scaled_to_200kV_R304_16degPierce30degJunction_beamline_sims_20240303.pdf|140 and 180 kV R28-2 operational settings scaled to 200 kV for R30-4]]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_28_2024&diff=30686Feb 28 20242024-02-28T13:52:20Z<p>Chgarcia: /* Updates */</p>
<hr />
<div>==From last time==<br />
<br />
* <br />
* Simulations<br />
** Max: <br />
*** Repeat simulations from today's presentation but with space charge ON and with Moller specs bunch charge / beam current. <br />
*** Add dipole field map to simulations.<br />
*** Add to simulations graphics location of first beam viewer screen<br />
*** Continue exploring option B, perhaps with slightly stronger focusing compared to option A(16 deg / 30 deg) Pierce angle cathode front end, but do this with space charge ON and with Moller spec bunch charge<br />
** Alicia: Add emittance to slides from today's presentation<br />
** Yan: Develop beam studies plan (ATLis) to implement BEFORE SAD for measuring beam size at Y-chamber viewer vs first solenoid BDL (or current) for R28 gun operating at 140 kV. Results will then be compared with beam envelope simulation results from Max and from Alicia.<br />
<br />
* ME<br />
** Carlos: <br />
*** Add to schedule fabrication of "plan B' second choice Pierce angle cathode front end. <br />
*** Check actual design and manufacturing progress of plan A (16 deg / 30 deg) Pierce angle cathode front end against schedule.<br />
*** Define milestones and deadlines<br />
* Documentation<br />
** Gabriel: start writing a technical note detailing the process and steps from concept anode-cathode geometry to production of electric field maps and implementation to GPT. Consideration such as puck position wrt to plan of the electrode hole must be described, as well as process for parametric geometry studies including Pierce angle, hole size, junction angle between spherical electrode and front end cathode. Include process for validating CST against POISSON, etc.<br />
<br />
<br />
==Updates==<br />
<br />
* Max:<br />
** 15° dipole simulated and compared with measurement<br />
*** discrepancy in horizontal (de)focusing yet to be understood<br />
*** measured skew coupling likely caused by VIP1I01, planning to mitigate it... could be included in GPT if needed<br />
*** these effects are small compared to the possible variations in gun optics; our not fully understanding them yet is not prohibitive to gun redesign<br />
** optimized lens settings with space charge: [[media:20240227 optimized lenses comparison 200kv.pdf|200 kV, solenoids SW vs. repaired CW]]<br />
*** all four setups are optimized independently for minimum beam sizes in MDR1I02 and MWF1I04<br />
*** beam size/divergence depends on space charge, but optimum BDL for solenoids is only weakly dependent<br />
*** SW solenoids cause emittance exchange due to gun astigmatism, but this gets removed by the second one, no significant difference downstream compared with CW<br />
** design strategy for Plan B electrode driven by possible failure modes: a) beam optics, b) FE / HV breakdown, c) something we are overlooking entirely<br />
*** a) not much freedom to further reduce the Pierce angle without moving the cathode in z, so we're not changing it; no obvious reason to want to increase the focusing strength from nominal<br />
*** b) the only degree of freedom is the junction angle; try to maximize it without exceeding surface-field threshold on lip. Gabriel to provide final numbers<br />
*** c) no idea what to do about this, so fingers crossed<br />
** Gabriel<br />
*** CST simulations looking at the gradient of the lip and junction for various junction angle options.<br />
**** [[media:R30-4 Junction angle.pdf|R30-4 junction angle and lip radius gradients vs junction angle]]<br />
<br />
=<br />=<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=File:R30-4_Junction_angle.pdf&diff=30685File:R30-4 Junction angle.pdf2024-02-28T13:52:10Z<p>Chgarcia: </p>
<hr />
<div></div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_28_2024&diff=30684Feb 28 20242024-02-28T13:51:39Z<p>Chgarcia: /* Updates */</p>
<hr />
<div>==From last time==<br />
<br />
* <br />
* Simulations<br />
** Max: <br />
*** Repeat simulations from today's presentation but with space charge ON and with Moller specs bunch charge / beam current. <br />
*** Add dipole field map to simulations.<br />
*** Add to simulations graphics location of first beam viewer screen<br />
*** Continue exploring option B, perhaps with slightly stronger focusing compared to option A(16 deg / 30 deg) Pierce angle cathode front end, but do this with space charge ON and with Moller spec bunch charge<br />
** Alicia: Add emittance to slides from today's presentation<br />
** Yan: Develop beam studies plan (ATLis) to implement BEFORE SAD for measuring beam size at Y-chamber viewer vs first solenoid BDL (or current) for R28 gun operating at 140 kV. Results will then be compared with beam envelope simulation results from Max and from Alicia.<br />
<br />
* ME<br />
** Carlos: <br />
*** Add to schedule fabrication of "plan B' second choice Pierce angle cathode front end. <br />
*** Check actual design and manufacturing progress of plan A (16 deg / 30 deg) Pierce angle cathode front end against schedule.<br />
*** Define milestones and deadlines<br />
* Documentation<br />
** Gabriel: start writing a technical note detailing the process and steps from concept anode-cathode geometry to production of electric field maps and implementation to GPT. Consideration such as puck position wrt to plan of the electrode hole must be described, as well as process for parametric geometry studies including Pierce angle, hole size, junction angle between spherical electrode and front end cathode. Include process for validating CST against POISSON, etc.<br />
<br />
<br />
==Updates==<br />
<br />
* Max:<br />
** 15° dipole simulated and compared with measurement<br />
*** discrepancy in horizontal (de)focusing yet to be understood<br />
*** measured skew coupling likely caused by VIP1I01, planning to mitigate it... could be included in GPT if needed<br />
*** these effects are small compared to the possible variations in gun optics; our not fully understanding them yet is not prohibitive to gun redesign<br />
** optimized lens settings with space charge: [[media:20240227 optimized lenses comparison 200kv.pdf|200 kV, solenoids SW vs. repaired CW]]<br />
*** all four setups are optimized independently for minimum beam sizes in MDR1I02 and MWF1I04<br />
*** beam size/divergence depends on space charge, but optimum BDL for solenoids is only weakly dependent<br />
*** SW solenoids cause emittance exchange due to gun astigmatism, but this gets removed by the second one, no significant difference downstream compared with CW<br />
** design strategy for Plan B electrode driven by possible failure modes: a) beam optics, b) FE / HV breakdown, c) something we are overlooking entirely<br />
*** a) not much freedom to further reduce the Pierce angle without moving the cathode in z, so we're not changing it; no obvious reason to want to increase the focusing strength from nominal<br />
*** b) the only degree of freedom is the junction angle; try to maximize it without exceeding surface-field threshold on lip. Gabriel to provide final numbers<br />
*** c) no idea what to do about this, so fingers crossed<br />
** Gabriel<br />
*** CST simulations looking at the gradient of the lip and junction for various junction angle options.<br />
****[[media:R30-4 Junction angle.pdf|R30-4 junction angle and lip radius gradients vs junction angle]]<br />
<br />
=<br />=<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_28_2024&diff=30683Feb 28 20242024-02-28T13:49:21Z<p>Chgarcia: /* Updates */</p>
<hr />
<div>==From last time==<br />
<br />
* <br />
* Simulations<br />
** Max: <br />
*** Repeat simulations from today's presentation but with space charge ON and with Moller specs bunch charge / beam current. <br />
*** Add dipole field map to simulations.<br />
*** Add to simulations graphics location of first beam viewer screen<br />
*** Continue exploring option B, perhaps with slightly stronger focusing compared to option A(16 deg / 30 deg) Pierce angle cathode front end, but do this with space charge ON and with Moller spec bunch charge<br />
** Alicia: Add emittance to slides from today's presentation<br />
** Yan: Develop beam studies plan (ATLis) to implement BEFORE SAD for measuring beam size at Y-chamber viewer vs first solenoid BDL (or current) for R28 gun operating at 140 kV. Results will then be compared with beam envelope simulation results from Max and from Alicia.<br />
<br />
* ME<br />
** Carlos: <br />
*** Add to schedule fabrication of "plan B' second choice Pierce angle cathode front end. <br />
*** Check actual design and manufacturing progress of plan A (16 deg / 30 deg) Pierce angle cathode front end against schedule.<br />
*** Define milestones and deadlines<br />
* Documentation<br />
** Gabriel: start writing a technical note detailing the process and steps from concept anode-cathode geometry to production of electric field maps and implementation to GPT. Consideration such as puck position wrt to plan of the electrode hole must be described, as well as process for parametric geometry studies including Pierce angle, hole size, junction angle between spherical electrode and front end cathode. Include process for validating CST against POISSON, etc.<br />
<br />
<br />
==Updates==<br />
<br />
* Max:<br />
** 15° dipole simulated and compared with measurement<br />
*** discrepancy in horizontal (de)focusing yet to be understood<br />
*** measured skew coupling likely caused by VIP1I01, planning to mitigate it... could be included in GPT if needed<br />
*** these effects are small compared to the possible variations in gun optics; our not fully understanding them yet is not prohibitive to gun redesign<br />
** optimized lens settings with space charge: [[media:20240227 optimized lenses comparison 200kv.pdf|200 kV, solenoids SW vs. repaired CW]]<br />
*** all four setups are optimized independently for minimum beam sizes in MDR1I02 and MWF1I04<br />
*** beam size/divergence depends on space charge, but optimum BDL for solenoids is only weakly dependent<br />
*** SW solenoids cause emittance exchange due to gun astigmatism, but this gets removed by the second one, no significant difference downstream compared with CW<br />
** design strategy for Plan B electrode driven by possible failure modes: a) beam optics, b) FE / HV breakdown, c) something we are overlooking entirely<br />
*** a) not much freedom to further reduce the Pierce angle without moving the cathode in z, so we're not changing it; no obvious reason to want to increase the focusing strength from nominal<br />
*** b) the only degree of freedom is the junction angle; try to maximize it without exceeding surface-field threshold on lip. Gabriel to provide final numbers<br />
*** c) no idea what to do about this, so fingers crossed<br />
** Gabriel<br />
*** CST simulations looking at the gradient of the lip and junction for various junction angle options.<br />
****<br />
<br />
=<br />=<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_28_2024&diff=30682Feb 28 20242024-02-28T13:46:37Z<p>Chgarcia: /* Updates */</p>
<hr />
<div>==From last time==<br />
<br />
* <br />
* Simulations<br />
** Max: <br />
*** Repeat simulations from today's presentation but with space charge ON and with Moller specs bunch charge / beam current. <br />
*** Add dipole field map to simulations.<br />
*** Add to simulations graphics location of first beam viewer screen<br />
*** Continue exploring option B, perhaps with slightly stronger focusing compared to option A(16 deg / 30 deg) Pierce angle cathode front end, but do this with space charge ON and with Moller spec bunch charge<br />
** Alicia: Add emittance to slides from today's presentation<br />
** Yan: Develop beam studies plan (ATLis) to implement BEFORE SAD for measuring beam size at Y-chamber viewer vs first solenoid BDL (or current) for R28 gun operating at 140 kV. Results will then be compared with beam envelope simulation results from Max and from Alicia.<br />
<br />
* ME<br />
** Carlos: <br />
*** Add to schedule fabrication of "plan B' second choice Pierce angle cathode front end. <br />
*** Check actual design and manufacturing progress of plan A (16 deg / 30 deg) Pierce angle cathode front end against schedule.<br />
*** Define milestones and deadlines<br />
* Documentation<br />
** Gabriel: start writing a technical note detailing the process and steps from concept anode-cathode geometry to production of electric field maps and implementation to GPT. Consideration such as puck position wrt to plan of the electrode hole must be described, as well as process for parametric geometry studies including Pierce angle, hole size, junction angle between spherical electrode and front end cathode. Include process for validating CST against POISSON, etc.<br />
<br />
<br />
==Updates==<br />
<br />
* Max:<br />
** 15° dipole simulated and compared with measurement<br />
*** discrepancy in horizontal (de)focusing yet to be understood<br />
*** measured skew coupling likely caused by VIP1I01, planning to mitigate it... could be included in GPT if needed<br />
*** these effects are small compared to the possible variations in gun optics; our not fully understanding them yet is not prohibitive to gun redesign<br />
** optimized lens settings with space charge: [[media:20240227 optimized lenses comparison 200kv.pdf|200 kV, solenoids SW vs. repaired CW]]<br />
*** all four setups are optimized independently for minimum beam sizes in MDR1I02 and MWF1I04<br />
*** beam size/divergence depends on space charge, but optimum BDL for solenoids is only weakly dependent<br />
*** SW solenoids cause emittance exchange due to gun astigmatism, but this gets removed by the second one, no significant difference downstream compared with CW<br />
** design strategy for Plan B electrode driven by possible failure modes: a) beam optics, b) FE / HV breakdown, c) something we are overlooking entirely<br />
*** a) not much freedom to further reduce the Pierce angle without moving the cathode in z, so we're not changing it; no obvious reason to want to increase the focusing strength from nominal<br />
*** b) the only degree of freedom is the junction angle; try to maximize it without exceeding surface-field threshold on lip. Gabriel to provide final numbers<br />
*** c) no idea what to do about this, so fingers crossed<br />
<br />
<br />
=<br />=<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_21_2024&diff=30678Feb 21 20242024-02-22T13:49:41Z<p>Chgarcia: /* Discussion */</p>
<hr />
<div>==From last time==<br />
<br />
* Beam simulations<br />
* ME<br />
** Gabriel provided Keith Harding with 3D model of the new Pierce cathode front end with 16 deg cone and 30 deg junction angle<br />
** They have now a 3D model of the front end piece with the corresponding specs before polishing. This drawing is going to be sent to the machine shop for fabricating two samples. One sample will polished. Then th un-polished and polished samples will be measured (hole diameter) to estimate how much the size increases after polishing. After that the model will be updated and sent back to Gabriel for cross-checking. The expectation is that the dimensions, (particularly hole diameter) after polishing should match the ones of the 3D model used for simulations.<br />
** Machine shop expect to have the two samples ready by end of February.<br />
* Technical Note<br />
** Gabriel to start drafting a procedure for developing electric fields maps in CST starting from ME models and implementing them in GPT<br />
** Max to coordinate the procedure writing with Gabriel and with Alicia to capture steps for model validation with beam-based measurements, and with full injector GPT model<br />
* <br />
<br />
==Discussion==<br />
<br />
* Max's [[media:20240221_Gun_matching.pdf|simulation results]]:<br />
** With optimized solenoid settings for R28 and different R30 cases, all reasonable gun models can be made to behave about the same. The 140 kV settings found this way are only 10% off from what was in the machine during setup with Wiens off.<br />
** Beam size in solenoids: useful lower limit determined by initial emittance and distances; upper limit determined by onset of emittance increase due to aberrations, RMS about 2 mm for CW (!) and 3 mm for SW<br />
*** This means the shorter the focal length (-> less astigmatism + big beam), the better the SW configuration. SW is worse only when Larmor rotation (irrelevant for round beam) causes more effective emittance increase than aberrations. Need to investigate this for a realistic range of beam parameters from the gun.<br />
** Alicia's [[media:Comparison_R282_R304_16degPierce30degJunction_beamline_sims_140kV180kVOps_140kV200kVMax_20240221_v2.pptx|simulation results in Power Point]], [[media:Comparison_R282_R304_16degPierce30degJunction_beamline_sims_140kV180kVOps_140kV200kVMax_20240221_v2.pdf|simulation results in PDF]]<br />
*** Discuss the objectives of the next simulation<br />
<br />
==Path forward, conclusions==<br />
<br />
* <br />
* Simulations<br />
** Max: <br />
*** Repeat simulations from today's presentation but with space charge ON and with Moller specs bunch charge / beam current. <br />
*** Add dipole field map to simulations.<br />
*** Add to simulations graphics location of first beam viewer screen<br />
*** Continue exploring option B, perhaps with slightly stronger focusing compared to option A(16 deg / 30 deg) Pierce angle cathode front end, but do this with space charge ON and with Moller spec bunch charge<br />
** Alicia: Add emittance to slides from today's presentation<br />
** Yan: Develop beam studies plan (ATLis) to implement BEFORE SAD for measuring beam size at Y-chamber viewer vs first solenoid BDL (or current) for R28 gun operating at 140 kV. Results will then be compared with beam envelope simulation results from Max and from Alicia.<br />
<br />
* ME<br />
** Carlos: <br />
*** Add to schedule fabrication of "plan B' second choice Pierce angle cathode front end. <br />
*** Check actual design and manufacturing progress of plan A (16 deg / 30 deg) Pierce angle cathode front end against schedule.<br />
*** Define milestones and deadlines<br />
* Documentation<br />
** Gabriel: start writing a technical note detailing the process and steps from concept anode-cathode geometry to production of electric field maps and implementation to GPT. Consideration such as puck position wrt to plan of the electrode hole must be described, as well as process for parametric geometry studies including Pierce angle, hole size, junction angle between spherical electrode and front end cathode. Include process for validating CST against POISSON, etc.<br />
<br />
=<br />=<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=File:Comparison_R282_R304_16degPierce30degJunction_beamline_sims_140kV180kVOps_140kV200kVMax_20240221_v2.pdf&diff=30677File:Comparison R282 R304 16degPierce30degJunction beamline sims 140kV180kVOps 140kV200kVMax 20240221 v2.pdf2024-02-22T13:49:24Z<p>Chgarcia: </p>
<hr />
<div></div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_21_2024&diff=30676Feb 21 20242024-02-22T13:48:14Z<p>Chgarcia: /* Discussion */</p>
<hr />
<div>==From last time==<br />
<br />
* Beam simulations<br />
* ME<br />
** Gabriel provided Keith Harding with 3D model of the new Pierce cathode front end with 16 deg cone and 30 deg junction angle<br />
** They have now a 3D model of the front end piece with the corresponding specs before polishing. This drawing is going to be sent to the machine shop for fabricating two samples. One sample will polished. Then th un-polished and polished samples will be measured (hole diameter) to estimate how much the size increases after polishing. After that the model will be updated and sent back to Gabriel for cross-checking. The expectation is that the dimensions, (particularly hole diameter) after polishing should match the ones of the 3D model used for simulations.<br />
** Machine shop expect to have the two samples ready by end of February.<br />
* Technical Note<br />
** Gabriel to start drafting a procedure for developing electric fields maps in CST starting from ME models and implementing them in GPT<br />
** Max to coordinate the procedure writing with Gabriel and with Alicia to capture steps for model validation with beam-based measurements, and with full injector GPT model<br />
* <br />
<br />
==Discussion==<br />
<br />
* Max's [[media:20240221_Gun_matching.pdf|simulation results]]:<br />
** With optimized solenoid settings for R28 and different R30 cases, all reasonable gun models can be made to behave about the same. The 140 kV settings found this way are only 10% off from what was in the machine during setup with Wiens off.<br />
** Beam size in solenoids: useful lower limit determined by initial emittance and distances; upper limit determined by onset of emittance increase due to aberrations, RMS about 2 mm for CW (!) and 3 mm for SW<br />
*** This means the shorter the focal length (-> less astigmatism + big beam), the better the SW configuration. SW is worse only when Larmor rotation (irrelevant for round beam) causes more effective emittance increase than aberrations. Need to investigate this for a realistic range of beam parameters from the gun.<br />
* Alicia's [[media:Comparison_R282_R304_16degPierce30degJunction_beamline_sims_140kV180kVOps_140kV200kVMax_20240221_v2.pptx|simulation results in Power Point]], [[media:Comparison_R282_R304_16degPierce30degJunction_beamline_sims_140kV180kVOps_140kV200kVMax_20240221_v2.pdf|simulation results in PDF]]<br />
** Discuss the objectives of the next simulation<br />
<br />
==Path forward, conclusions==<br />
<br />
* <br />
* Simulations<br />
** Max: <br />
*** Repeat simulations from today's presentation but with space charge ON and with Moller specs bunch charge / beam current. <br />
*** Add dipole field map to simulations.<br />
*** Add to simulations graphics location of first beam viewer screen<br />
*** Continue exploring option B, perhaps with slightly stronger focusing compared to option A(16 deg / 30 deg) Pierce angle cathode front end, but do this with space charge ON and with Moller spec bunch charge<br />
** Alicia: Add emittance to slides from today's presentation<br />
** Yan: Develop beam studies plan (ATLis) to implement BEFORE SAD for measuring beam size at Y-chamber viewer vs first solenoid BDL (or current) for R28 gun operating at 140 kV. Results will then be compared with beam envelope simulation results from Max and from Alicia.<br />
<br />
* ME<br />
** Carlos: <br />
*** Add to schedule fabrication of "plan B' second choice Pierce angle cathode front end. <br />
*** Check actual design and manufacturing progress of plan A (16 deg / 30 deg) Pierce angle cathode front end against schedule.<br />
*** Define milestones and deadlines<br />
* Documentation<br />
** Gabriel: start writing a technical note detailing the process and steps from concept anode-cathode geometry to production of electric field maps and implementation to GPT. Consideration such as puck position wrt to plan of the electrode hole must be described, as well as process for parametric geometry studies including Pierce angle, hole size, junction angle between spherical electrode and front end cathode. Include process for validating CST against POISSON, etc.<br />
<br />
=<br />=<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_21_2024&diff=30675Feb 21 20242024-02-22T13:47:36Z<p>Chgarcia: /* Discussion */</p>
<hr />
<div>==From last time==<br />
<br />
* Beam simulations<br />
* ME<br />
** Gabriel provided Keith Harding with 3D model of the new Pierce cathode front end with 16 deg cone and 30 deg junction angle<br />
** They have now a 3D model of the front end piece with the corresponding specs before polishing. This drawing is going to be sent to the machine shop for fabricating two samples. One sample will polished. Then th un-polished and polished samples will be measured (hole diameter) to estimate how much the size increases after polishing. After that the model will be updated and sent back to Gabriel for cross-checking. The expectation is that the dimensions, (particularly hole diameter) after polishing should match the ones of the 3D model used for simulations.<br />
** Machine shop expect to have the two samples ready by end of February.<br />
* Technical Note<br />
** Gabriel to start drafting a procedure for developing electric fields maps in CST starting from ME models and implementing them in GPT<br />
** Max to coordinate the procedure writing with Gabriel and with Alicia to capture steps for model validation with beam-based measurements, and with full injector GPT model<br />
* <br />
<br />
==Discussion==<br />
<br />
* Max's [[media:20240221_Gun_matching.pdf|simulation results]]:<br />
** With optimized solenoid settings for R28 and different R30 cases, all reasonable gun models can be made to behave about the same. The 140 kV settings found this way are only 10% off from what was in the machine during setup with Wiens off.<br />
** Beam size in solenoids: useful lower limit determined by initial emittance and distances; upper limit determined by onset of emittance increase due to aberrations, RMS about 2 mm for CW (!) and 3 mm for SW<br />
*** This means the shorter the focal length (-> less astigmatism + big beam), the better the SW configuration. SW is worse only when Larmor rotation (irrelevant for round beam) causes more effective emittance increase than aberrations. Need to investigate this for a realistic range of beam parameters from the gun.<br />
* Alicia's [[media:Comparison_R282_R304_16degPierce30degJunction_beamline_sims_140kV180kVOps_140kV200kVMax_20240221_v2.pptx|simulation results in Power Point]]<br />
** Discuss the objectives of the next simulation<br />
<br />
==Path forward, conclusions==<br />
<br />
* <br />
* Simulations<br />
** Max: <br />
*** Repeat simulations from today's presentation but with space charge ON and with Moller specs bunch charge / beam current. <br />
*** Add dipole field map to simulations.<br />
*** Add to simulations graphics location of first beam viewer screen<br />
*** Continue exploring option B, perhaps with slightly stronger focusing compared to option A(16 deg / 30 deg) Pierce angle cathode front end, but do this with space charge ON and with Moller spec bunch charge<br />
** Alicia: Add emittance to slides from today's presentation<br />
** Yan: Develop beam studies plan (ATLis) to implement BEFORE SAD for measuring beam size at Y-chamber viewer vs first solenoid BDL (or current) for R28 gun operating at 140 kV. Results will then be compared with beam envelope simulation results from Max and from Alicia.<br />
<br />
* ME<br />
** Carlos: <br />
*** Add to schedule fabrication of "plan B' second choice Pierce angle cathode front end. <br />
*** Check actual design and manufacturing progress of plan A (16 deg / 30 deg) Pierce angle cathode front end against schedule.<br />
*** Define milestones and deadlines<br />
* Documentation<br />
** Gabriel: start writing a technical note detailing the process and steps from concept anode-cathode geometry to production of electric field maps and implementation to GPT. Consideration such as puck position wrt to plan of the electrode hole must be described, as well as process for parametric geometry studies including Pierce angle, hole size, junction angle between spherical electrode and front end cathode. Include process for validating CST against POISSON, etc.<br />
<br />
=<br />=<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=File:Comparison_R282_R304_16degPierce30degJunction_beamline_sims_140kV180kVOps_140kV200kVMax_20240221_v2.pptx&diff=30664File:Comparison R282 R304 16degPierce30degJunction beamline sims 140kV180kVOps 140kV200kVMax 20240221 v2.pptx2024-02-21T18:31:52Z<p>Chgarcia: </p>
<hr />
<div></div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_21_2024&diff=30663Feb 21 20242024-02-21T18:31:31Z<p>Chgarcia: /* Discussion */</p>
<hr />
<div>==From last time==<br />
<br />
* Beam simulations<br />
* ME<br />
** Gabriel provided Keith Harding with 3D model of the new Pierce cathode front end with 16 deg cone and 30 deg junction angle<br />
** They have now a 3D model of the front end piece with the corresponding specs before polishing. This drawing is going to be sent to the machine shop for fabricating two samples. One sample will polished. Then th un-polished and polished samples will be measured (hole diameter) to estimate how much the size increases after polishing. After that the model will be updated and sent back to Gabriel for cross-checking. The expectation is that the dimensions, (particularly hole diameter) after polishing should match the ones of the 3D model used for simulations.<br />
** Machine shop expect to have the two samples ready by end of February.<br />
* Technical Note<br />
** Gabriel to start drafting a procedure for developing electric fields maps in CST starting from ME models and implementing them in GPT<br />
** Max to coordinate the procedure writing with Gabriel and with Alicia to capture steps for model validation with beam-based measurements, and with full injector GPT model<br />
* <br />
<br />
==Discussion==<br />
<br />
* Max's [[media:20240221_Gun_matching.pdf|simulation results]]:<br />
** With optimized solenoid settings for R28 and different R30 cases, all reasonable gun models can be made to behave about the same. The 140 kV settings found this way are only 10% off from what was in the machine during setup with Wiens off.<br />
** Beam size in solenoids: useful lower limit determined by initial emittance and distances; upper limit determined by onset of emittance increase due to aberrations, RMS about 2 mm for CW (!) and 3 mm for SW<br />
*** This means the shorter the focal length (-> less astigmatism + big beam), the better the SW configuration. SW is worse only when Larmor rotation (irrelevant for round beam) causes more effective emittance increase than aberrations. Need to investigate this for a realistic range of beam parameters from the gun.<br />
* Alicia's [[media:Comparison_R282_R304_16degPierce30degJunction_beamline_sims_140kV180kVOps_140kV200kVMax_20240221_v2.pptx|simulation results]]<br />
** Discuss the objectives of the next simulation<br />
<br />
==Path forward, conclusions==<br />
<br />
* <br />
* Simulations<br />
** Max: <br />
*** Repeat simulations from today's presentation but with space charge ON and with Moller specs bunch charge / beam current. <br />
*** Add dipole field map to simulations.<br />
*** Add to simulations graphics location of first beam viewer screen<br />
*** Continue exploring option B, perhaps with slightly stronger focusing compared to option A(16 deg / 30 deg) Pierce angle cathode front end, but do this with space charge ON and with Moller spec bunch charge<br />
** Alicia: Add emittance to slides from today's presentation<br />
** Yan: Develop beam studies plan (ATLis) to implement BEFORE SAD for measuring beam size at Y-chamber viewer vs first solenoid BDL (or current) for R28 gun operating at 140 kV. Results will then be compared with beam envelope simulation results from Max and from Alicia.<br />
<br />
* ME<br />
** Carlos: <br />
*** Add to schedule fabrication of "plan B' second choice Pierce angle cathode front end. <br />
*** Check actual design and manufacturing progress of plan A (16 deg / 30 deg) Pierce angle cathode front end against schedule.<br />
*** Define milestones and deadlines<br />
* Documentation<br />
** Gabriel: start writing a technical note detailing the process and steps from concept anode-cathode geometry to production of electric field maps and implementation to GPT. Consideration such as puck position wrt to plan of the electrode hole must be described, as well as process for parametric geometry studies including Pierce angle, hole size, junction angle between spherical electrode and front end cathode. Include process for validating CST against POISSON, etc.<br />
<br />
=<br />=<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_21_2024&diff=30662Feb 21 20242024-02-21T18:29:35Z<p>Chgarcia: /* Discussion */</p>
<hr />
<div>==From last time==<br />
<br />
* Beam simulations<br />
* ME<br />
** Gabriel provided Keith Harding with 3D model of the new Pierce cathode front end with 16 deg cone and 30 deg junction angle<br />
** They have now a 3D model of the front end piece with the corresponding specs before polishing. This drawing is going to be sent to the machine shop for fabricating two samples. One sample will polished. Then th un-polished and polished samples will be measured (hole diameter) to estimate how much the size increases after polishing. After that the model will be updated and sent back to Gabriel for cross-checking. The expectation is that the dimensions, (particularly hole diameter) after polishing should match the ones of the 3D model used for simulations.<br />
** Machine shop expect to have the two samples ready by end of February.<br />
* Technical Note<br />
** Gabriel to start drafting a procedure for developing electric fields maps in CST starting from ME models and implementing them in GPT<br />
** Max to coordinate the procedure writing with Gabriel and with Alicia to capture steps for model validation with beam-based measurements, and with full injector GPT model<br />
* <br />
<br />
==Discussion==<br />
<br />
* Max's [[media:20240221_Gun_matching.pdf|simulation results]]:<br />
** With optimized solenoid settings for R28 and different R30 cases, all reasonable gun models can be made to behave about the same. The 140 kV settings found this way are only 10% off from what was in the machine during setup with Wiens off.<br />
** Beam size in solenoids: useful lower limit determined by initial emittance and distances; upper limit determined by onset of emittance increase due to aberrations, RMS about 2 mm for CW (!) and 3 mm for SW<br />
*** This means the shorter the focal length (-> less astigmatism + big beam), the better the SW configuration. SW is worse only when Larmor rotation (irrelevant for round beam) causes more effective emittance increase than aberrations. Need to investigate this for a realistic range of beam parameters from the gun.<br />
* Alicia's<br />
** Discuss the objectives of the next simulation<br />
<br />
==Path forward, conclusions==<br />
<br />
* <br />
* Simulations<br />
** Max: <br />
*** Repeat simulations from today's presentation but with space charge ON and with Moller specs bunch charge / beam current. <br />
*** Add dipole field map to simulations.<br />
*** Add to simulations graphics location of first beam viewer screen<br />
*** Continue exploring option B, perhaps with slightly stronger focusing compared to option A(16 deg / 30 deg) Pierce angle cathode front end, but do this with space charge ON and with Moller spec bunch charge<br />
** Alicia: Add emittance to slides from today's presentation<br />
** Yan: Develop beam studies plan (ATLis) to implement BEFORE SAD for measuring beam size at Y-chamber viewer vs first solenoid BDL (or current) for R28 gun operating at 140 kV. Results will then be compared with beam envelope simulation results from Max and from Alicia.<br />
<br />
* ME<br />
** Carlos: <br />
*** Add to schedule fabrication of "plan B' second choice Pierce angle cathode front end. <br />
*** Check actual design and manufacturing progress of plan A (16 deg / 30 deg) Pierce angle cathode front end against schedule.<br />
*** Define milestones and deadlines<br />
* Documentation<br />
** Gabriel: start writing a technical note detailing the process and steps from concept anode-cathode geometry to production of electric field maps and implementation to GPT. Consideration such as puck position wrt to plan of the electrode hole must be described, as well as process for parametric geometry studies including Pierce angle, hole size, junction angle between spherical electrode and front end cathode. Include process for validating CST against POISSON, etc.<br />
<br />
=<br />=<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_21_2024&diff=30661Feb 21 20242024-02-21T18:08:48Z<p>Chgarcia: /* Path forward, conclusions */</p>
<hr />
<div>==From last time==<br />
<br />
* Beam simulations<br />
* ME<br />
** Gabriel provided Keith Harding with 3D model of the new Pierce cathode front end with 16 deg cone and 30 deg junction angle<br />
** They have now a 3D model of the front end piece with the corresponding specs before polishing. This drawing is going to be sent to the machine shop for fabricating two samples. One sample will polished. Then th un-polished and polished samples will be measured (hole diameter) to estimate how much the size increases after polishing. After that the model will be updated and sent back to Gabriel for cross-checking. The expectation is that the dimensions, (particularly hole diameter) after polishing should match the ones of the 3D model used for simulations.<br />
** Machine shop expect to have the two samples ready by end of February.<br />
* Technical Note<br />
** Gabriel to start drafting a procedure for developing electric fields maps in CST starting from ME models and implementing them in GPT<br />
** Max to coordinate the procedure writing with Gabriel and with Alicia to capture steps for model validation with beam-based measurements, and with full injector GPT model<br />
* <br />
<br />
==Discussion==<br />
<br />
* Max's [[media:20240221_Gun_matching.pdf|simulation results]]:<br />
** With optimized solenoid settings for R28 and different R30 cases, all reasonable gun models can be made to behave about the same. The 140 kV settings found this way are only 10% off from what was in the machine during setup with Wiens off.<br />
** Beam size in solenoids: useful lower limit determined by initial emittance and distances; upper limit determined by onset of emittance increase due to aberrations, RMS about 2 mm for CW (!) and 3 mm for SW<br />
*** This means the shorter the focal length (-> less astigmatism + big beam), the better the SW configuration. SW is worse only when Larmor rotation (irrelevant for round beam) causes more effective emittance increase than aberrations. Need to investigate this for a realistic range of beam parameters from the gun.<br />
* Discuss the objectives of the next simulation<br />
<br />
==Path forward, conclusions==<br />
<br />
* <br />
* Simulations<br />
** Max: <br />
*** Repeat simulations from today's presentation but with space charge ON and with Moller specs bunch charge / beam current. <br />
*** Add dipole field map to simulations.<br />
*** Add to simulations graphics location of first beam viewer screen<br />
*** Continue exploring option B, perhaps with slightly stronger focusing compared to option A(16 deg / 30 deg) Pierce angle cathode front end, but do this with space charge ON and with Moller spec bunch charge<br />
** Alicia: Add emittance to slides from today's presentation<br />
** Yan: Develop beam studies plan (ATLis) to implement BEFORE SAD for measuring beam size at Y-chamber viewer vs first solenoid BDL (or current) for R28 gun operating at 140 kV. Results will then be compared with beam envelope simulation results from Max and from Alicia.<br />
<br />
* ME<br />
** Carlos: <br />
*** Add to schedule fabrication of "plan B' second choice Pierce angle cathode front end. <br />
*** Check actual design and manufacturing progress of plan A (16 deg / 30 deg) Pierce angle cathode front end against schedule.<br />
*** Define milestones and deadlines<br />
* Documentation<br />
** Gabriel: start writing a technical note detailing the process and steps from concept anode-cathode geometry to production of electric field maps and implementation to GPT. Consideration such as puck position wrt to plan of the electrode hole must be described, as well as process for parametric geometry studies including Pierce angle, hole size, junction angle between spherical electrode and front end cathode. Include process for validating CST against POISSON, etc.<br />
<br />
=<br />=<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_21_2024&diff=30660Feb 21 20242024-02-21T17:57:11Z<p>Chgarcia: /* Path forward, conclusions */</p>
<hr />
<div>==From last time==<br />
<br />
* Beam simulations<br />
* ME<br />
** Gabriel provided Keith Harding with 3D model of the new Pierce cathode front end with 16 deg cone and 30 deg junction angle<br />
** They have now a 3D model of the front end piece with the corresponding specs before polishing. This drawing is going to be sent to the machine shop for fabricating two samples. One sample will polished. Then th un-polished and polished samples will be measured (hole diameter) to estimate how much the size increases after polishing. After that the model will be updated and sent back to Gabriel for cross-checking. The expectation is that the dimensions, (particularly hole diameter) after polishing should match the ones of the 3D model used for simulations.<br />
** Machine shop expect to have the two samples ready by end of February.<br />
* Technical Note<br />
** Gabriel to start drafting a procedure for developing electric fields maps in CST starting from ME models and implementing them in GPT<br />
** Max to coordinate the procedure writing with Gabriel and with Alicia to capture steps for model validation with beam-based measurements, and with full injector GPT model<br />
* <br />
<br />
==Discussion==<br />
<br />
* Max's [[media:20240221_Gun_matching.pdf|simulation results]]:<br />
** With optimized solenoid settings for R28 and different R30 cases, all reasonable gun models can be made to behave about the same. The 140 kV settings found this way are only 10% off from what was in the machine during setup with Wiens off.<br />
** Beam size in solenoids: useful lower limit determined by initial emittance and distances; upper limit determined by onset of emittance increase due to aberrations, RMS about 2 mm for CW (!) and 3 mm for SW<br />
*** This means the shorter the focal length (-> less astigmatism + big beam), the better the SW configuration. SW is worse only when Larmor rotation (irrelevant for round beam) causes more effective emittance increase than aberrations. Need to investigate this for a realistic range of beam parameters from the gun.<br />
* Discuss the objectives of the next simulation<br />
<br />
==Path forward, conclusions==<br />
<br />
* <br />
* Simulations<br />
** Max: Repeat simulations from today's presentation but with space charge ON and with Moller specs bunch charge / beam current. Add dipole field map to simulations.<br />
** Alicia: Add emittance to slides from today's presentation<br />
** Yan: Develop beam studies plan (ATLis) to implement BEFORE SAD for measuring beam size at Y-chamber viewer vs first solenoid BDL (or current) for R28 gun operating at 140 kV. Results will then be compared with beam envelope simulation results from Max and from Alicia.<br />
<br />
* ME<br />
** Carlos: Add to schedule fabrication of "plan B' second choice Pierce angle cathode front end. Check actual design and manufacturing progress of plan A (16 deg / 30 deg) Pierce angle cathode front end against schedule.<br />
<br />
=<br />=<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_21_2024&diff=30659Feb 21 20242024-02-21T17:44:31Z<p>Chgarcia: /* Path forward, conclusions */</p>
<hr />
<div>==From last time==<br />
<br />
* Beam simulations<br />
* ME<br />
** Gabriel provided Keith Harding with 3D model of the new Pierce cathode front end with 16 deg cone and 30 deg junction angle<br />
** They have now a 3D model of the front end piece with the corresponding specs before polishing. This drawing is going to be sent to the machine shop for fabricating two samples. One sample will polished. Then th un-polished and polished samples will be measured (hole diameter) to estimate how much the size increases after polishing. After that the model will be updated and sent back to Gabriel for cross-checking. The expectation is that the dimensions, (particularly hole diameter) after polishing should match the ones of the 3D model used for simulations.<br />
** Machine shop expect to have the two samples ready by end of February.<br />
* Technical Note<br />
** Gabriel to start drafting a procedure for developing electric fields maps in CST starting from ME models and implementing them in GPT<br />
** Max to coordinate the procedure writing with Gabriel and with Alicia to capture steps for model validation with beam-based measurements, and with full injector GPT model<br />
* <br />
<br />
==Discussion==<br />
<br />
* Max's [[media:20240221_Gun_matching.pdf|simulation results]]:<br />
** With optimized solenoid settings for R28 and different R30 cases, all reasonable gun models can be made to behave about the same. The 140 kV settings found this way are only 10% off from what was in the machine during setup with Wiens off.<br />
** Beam size in solenoids: useful lower limit determined by initial emittance and distances; upper limit determined by onset of emittance increase due to aberrations, RMS about 2 mm for CW (!) and 3 mm for SW<br />
*** This means the shorter the focal length (-> less astigmatism + big beam), the better the SW configuration. SW is worse only when Larmor rotation (irrelevant for round beam) causes more effective emittance increase than aberrations. Need to investigate this for a realistic range of beam parameters from the gun.<br />
* Discuss the objectives of the next simulation<br />
<br />
==Path forward, conclusions==<br />
<br />
* <br />
* Simulations<br />
** Max: Repeat simulations from today's presentation but with space charge ON and with Moller specs bunch charge / beam current<br />
** Alicia: Add emittance to slides from today's presentation<br />
** Yan: Develop beam studies plan (ATLis) to implement BEFORE SAD for measuring beam size at Y-chamber viewer vs first solenoid BDL (or current) for R28 gun operating at 140 kV. Results will then be compared with beam envelope simulation results from Max and from Alicia.<br />
<br />
* ME<br />
** Carlos: Add to schedule fabrication of "plan B' second choice Pierce angle cathode front end. Check actual design and manufacturing progress of plan A (16 deg / 30 deg) Pierce angle cathode front end against schedule.<br />
<br />
=<br />=<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_21_2024&diff=30658Feb 21 20242024-02-21T17:28:48Z<p>Chgarcia: /* Path forward, conclusions */</p>
<hr />
<div>==From last time==<br />
<br />
* Beam simulations<br />
* ME<br />
** Gabriel provided Keith Harding with 3D model of the new Pierce cathode front end with 16 deg cone and 30 deg junction angle<br />
** They have now a 3D model of the front end piece with the corresponding specs before polishing. This drawing is going to be sent to the machine shop for fabricating two samples. One sample will polished. Then th un-polished and polished samples will be measured (hole diameter) to estimate how much the size increases after polishing. After that the model will be updated and sent back to Gabriel for cross-checking. The expectation is that the dimensions, (particularly hole diameter) after polishing should match the ones of the 3D model used for simulations.<br />
** Machine shop expect to have the two samples ready by end of February.<br />
* Technical Note<br />
** Gabriel to start drafting a procedure for developing electric fields maps in CST starting from ME models and implementing them in GPT<br />
** Max to coordinate the procedure writing with Gabriel and with Alicia to capture steps for model validation with beam-based measurements, and with full injector GPT model<br />
* <br />
<br />
==Discussion==<br />
<br />
* Max's [[media:20240221_Gun_matching.pdf|simulation results]]:<br />
** With optimized solenoid settings for R28 and different R30 cases, all reasonable gun models can be made to behave about the same. The 140 kV settings found this way are only 10% off from what was in the machine during setup with Wiens off.<br />
** Beam size in solenoids: useful lower limit determined by initial emittance and distances; upper limit determined by onset of emittance increase due to aberrations, RMS about 2 mm for CW (!) and 3 mm for SW<br />
*** This means the shorter the focal length (-> less astigmatism + big beam), the better the SW configuration. SW is worse only when Larmor rotation (irrelevant for round beam) causes more effective emittance increase than aberrations. Need to investigate this for a realistic range of beam parameters from the gun.<br />
* Discuss the objectives of the next simulation<br />
<br />
==Path forward, conclusions==<br />
<br />
* Simulations<br />
<br />
* ME<br />
<br />
=<br />=<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_21_2024&diff=30653Feb 21 20242024-02-19T16:54:46Z<p>Chgarcia: </p>
<hr />
<div>==From last time==<br />
<br />
* Beam simulations<br />
* ME<br />
** Gabriel provided Keith Harding with 3D model of the new Pierce cathode front end with 16 deg cone and 30 deg junction angle<br />
** They have now a 3D model of the front end piece with the corresponding specs before polishing. This drawing is going to be sent to the machine shop for fabricating two samples. One sample will polished. Then th un-polished and polished samples will be measured (hole diameter) to estimate how much the size increases after polishing. After that the model will be updated and sent back to Gabriel for cross-checking. The expectation is that the dimensions, (particularly hole diameter) after polishing should match the ones of the 3D model used for simulations.<br />
** Machine shop expect to have the two samples ready by end of February.<br />
* Technical Note<br />
** Gabriel to start drafting a procedure for developing electric fields maps in CST starting from ME models and implementing them in GPT<br />
** Max to coordinate the procedure writing with Gabriel and with Alicia to capture steps for model validation with beam-based measurements, and with full injector GPT model<br />
* <br />
<br />
==Discussion==<br />
<br />
* <span>Discuss the objectives of the next simulation</span><br />
<br />
==Path forward, conclusions==<br />
<br />
* Simulations<br />
* ME<br />
<br />
=<br />=<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_21_2024&diff=30652Feb 21 20242024-02-19T16:54:32Z<p>Chgarcia: /* Path forward, conclusions */</p>
<hr />
<div>==From last time==<br />
<br />
* Beam simulations<br />
* ME<br />
** Gabriel provided Keith Harding with 3D model of the new Pierce cathode front end with 16 deg cone and 30 deg junction angle<br />
** They have now a 3D model of the front end piece with the corresponding specs before polishing. This drawing is going to be sent to the machine shop for fabricating two samples. One sample will polished. Then th un-polished and polished samples will be measured (hole diameter) to estimate how much the size increases after polishing. After that the model will be updated and sent back to Gabriel for cross-checking. The expectation is that the dimensions, (particularly hole diameter) after polishing should match the ones of the 3D model used for simulations.<br />
** Machine shop expect to have the two samples ready by end of February.<br />
* Technical Note<br />
** Gabriel to start drafting a procedure for developing electric fields maps in CST starting from ME models and implementing them in GPT<br />
** Max to coordinate the procedure writing with Gabriel and with Alicia to capture steps for model validation with beam-based measurements, and with full injector GPT model<br />
*<br />
<br />
==Discussion==<br />
<br />
* <span>Discuss the objectives of the next simulation</span><br />
<br />
==Path forward, conclusions==<br />
<br />
* Simulations<br />
* ME<br />
<br />
====<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_21_2024&diff=30651Feb 21 20242024-02-19T16:54:19Z<p>Chgarcia: /* From last time */</p>
<hr />
<div>==From last time==<br />
<br />
* Beam simulations<br />
* ME<br />
** Gabriel provided Keith Harding with 3D model of the new Pierce cathode front end with 16 deg cone and 30 deg junction angle<br />
** They have now a 3D model of the front end piece with the corresponding specs before polishing. This drawing is going to be sent to the machine shop for fabricating two samples. One sample will polished. Then th un-polished and polished samples will be measured (hole diameter) to estimate how much the size increases after polishing. After that the model will be updated and sent back to Gabriel for cross-checking. The expectation is that the dimensions, (particularly hole diameter) after polishing should match the ones of the 3D model used for simulations.<br />
** Machine shop expect to have the two samples ready by end of February.<br />
* Technical Note<br />
** Gabriel to start drafting a procedure for developing electric fields maps in CST starting from ME models and implementing them in GPT<br />
** Max to coordinate the procedure writing with Gabriel and with Alicia to capture steps for model validation with beam-based measurements, and with full injector GPT model<br />
*<br />
<br />
==Discussion==<br />
<br />
* <span>Discuss the objectives of the next simulation</span><br />
<br />
==Path forward, conclusions==<br />
<br />
* Simulations<br />
* ME<br />
<br />
<br />
<br />
====<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_21_2024&diff=30650Feb 21 20242024-02-19T16:53:24Z<p>Chgarcia: Created page with "==From last time== * Beam simulations * ME ** Gabriel provided Keith Harding with 3D model of the new Pierce cathode front end with 16 deg cone and 30 deg junction angle ** T..."</p>
<hr />
<div>==From last time==<br />
<br />
* Beam simulations<br />
* ME<br />
** Gabriel provided Keith Harding with 3D model of the new Pierce cathode front end with 16 deg cone and 30 deg junction angle<br />
** They have now a 3D model of the front end piece with the corresponding specs before polishing. This drawing is going to be sent to the machine shop for fabricating two samples. One sample will polished. Then th un-polished and polished samples will be measured (hole diameter) to estimate how much the size increases after polishing. After that the model will be updated and sent back to Gabriel for cross-checking. The expectation is that the dimensions, (particularly hole diameter) after polishing should match the ones of the 3D model used for simulations.<br />
** Machine shop expect to have the two samples ready by end of February.<br />
<br />
<br />
<br />
==Discussion==<br />
<br />
* <span>Discuss the objectives of the next simulation</span><br />
<br />
==Path forward, conclusions==<br />
<br />
* Simulations<br />
* ME<br />
<br />
<br />
<br />
====<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=200_kV_Polarized_Gun&diff=30649200 kV Polarized Gun2024-02-19T16:42:28Z<p>Chgarcia: /* R30-4 200 kV Gun SAD 2024 Planning Meetings */</p>
<hr />
<div>* The 200 kV gun (R30-3 with spherical electrode and 18" gun HVC) was installed in CEBAF during SAD 2023.<br />
<br />
* This gun performed as designed in terms of vacuum, and high voltage: no field emission at 200 kV after conditioning with Kr to ~240 kV.<br />
* It has two problems:<br />
** The beam waist is ~ 6 cm downstream of the GaAs wafer, compared to ~ 40 cm from the Tee electrode 14" HVC R28-2 gun operated in CEBAF for years at 130 kV.<br />
** It was a not possible to obtain the laser retro-reflection.<br />
* The gun was then removed from the injector and replaced with the R28-2 gun.<br />
* The SAD 2024 links below capture the planning for fixing these problems in the R30-3 gun (which will be version R30-4) and for installing it in May 2024.<br />
<br />
<br />
==R30-4 200 kV Gun SharePoint site==<br />
[https://jeffersonlab.sharepoint.com/:f:/s/CIS/Ejp9S0WdeXtPgFm_bwwkuEAB0gEzYKg7Ci0UfKK8qQnPfQ?e=1tfGAH R30-4 200 kV SharePoint site]<br />
<br />
<br />
Contains:<br />
* Pierce cathode end piece geometry and beam parameter space table<br />
* Notes, studies, and documentation<br />
* Electrostatics and beam dynamics modeling and simulation results<br />
<br />
==R30-4 200 kV Gun SAD 2024 Planning Meetings==<br />
<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Jan_05_2024 Jan 05, 2024]<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Jan_10_2024 Jan 10,2024]<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Jan_17_2024 Jan 17, 2024]<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Jan_24_2024 Jan 24, 2024]<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Jan_30_2024 Jan 31, 2024]<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Feb_7_2024 Feb 7, 2024]<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Feb_14_2024 Feb 14, 2024]<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Feb_21_2024 Feb 21, 2024]<br />
<br />
==R30-3 200 kV Gun SAD 2023 Installation Links==<br />
<br />
* ATLIS => https://tasklists.jlab.org/atlis/tasks/108541<br />
* Marcy's Gantt chart goes here => https://jeffersonlab-my.sharepoint.com/:x:/g/personal/marcy_jlab_org/EUe-xbLpNR1IsV28fyi20FUBC4bUllOnMnAYlXemA7C82Q<br />
* List of photocathodes at end of Phase 1 (5/10/2021) - https://logbooks.jlab.org/entry/3876517<br />
<br />
==R30-3 200 kV Gun SAD 2023 Planning Meetings==<br />
<br />
* Feb 20, 2023 => * Carlos SAD schedule [[Media:Gun swap planning 1 week before and 1 week after SAD start.pptx]]<br />
* Feb 02, 2022 => [[Feb 2, 2022 - Group meeting]] - Group meeting + 200 kV gun<br />
* Jan 26, 2022 => [[200 kV Gun - Jan 26, 2022]]<br />
<br />
==Links==<br />
<br />
* [https://wiki.jlab.org/ciswiki/index.php/18%22_Photogun_ala_GTS Carlos 18" Gun Page]<br />
* Gun Anode - Carlos's update https://wiki.jlab.org/ciswiki/index.php/Anode</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_14_2024&diff=30645Feb 14 20242024-02-15T14:10:28Z<p>Chgarcia: /* Path forward, conclusions */</p>
<hr />
<div>==From last time==<br />
<br />
* Plan A is the 16°/30° design. We are going to start the design/fabrication process to quickly get a practice part and go through all the steps.<br />
* Alicia's GPT simulations of the injector with Max's distributions indicate all models from 15 to 18 degrees should be manageable. Higher Pierce angles (shorter focal lengths) give a large beam size in the first lens and give high transmission loss at apertures, but the latter is because everything has so far been simulated with the same lens strengths. Max and Alicia will continue this work to re-match the optics for each case to see if the whole system of gun + 1 or 2 lenses actually differs. These studies may identify a suitable Plan B geometry and tell us how much deviation from the nominal geometry can be tolerated.<br />
* Meeting with Keith on Friday to get the ME design started.<br />
* Presentation at the upcoming B-Team meeting (2/13/24) about the strategy followed to solve the R30-3 focusing problem. Carlos will make some brief introductory remarks; Max and Alicia will decide to divide the rest of the work as it makes sense.[[media:R30-4 gun plan for BTeam meeting February 13 2024.pdf|Presentation can be found here]]<br />
<br />
==Discussion==<br />
<br />
* ME design<br />
** Keith Harding attended the meeting. He talked to Vince and both developed a plan to control the hole size as best as possible per design.<br />
**# Keith will send Vince a draft drawing with hole diameter 0.010" smaller than per design, with a 0.002" radius.<br />
**# The shop will make two samples<br />
**# One sample will get mechanically polished per our procedure using the tumbler and diamond paste<br />
**# The hole diameter will be measured in the un-polished, and polished sample and compared. This will tell us how much the hole diameter increases after polishing<br />
**# Produce final drawing<br />
**# Fabricate final design part + 1 spare<br />
** Modeling and simulations<br />
*** Max and Carlos received the following message from Matt: "...check that your 16 degree electrode properly matches into the first solenoid set to a realistic value that puts a beam waist at the 15 degree dipole. Good news, we know what this solenoid setting is, we use it today".<br /><br />
<br />
==Path forward, conclusions==<br />
<br />
* Wrapping up simulations and forecasting simulations after measuring final piece hole size and puck recess<br />
** Alicia to optimize injector settings at 200 kV for R30-4 solution, using counter wound FX solenoids (the version which is still not fixed in regards to the middle plate).<br />
** Model injector at 180 kV for R30-4 using actual machine setting from the R28-2 run in the machine<br />
* Updates from Carlos:<br />
** Preparing for practicing polishing on available stainless pieces similar in size to the cathode Pierce front end<br /><br />
** Measuring holes size of test piece before and after polishing<br />
** Develop plan for puck test on manufactured piece for measuring wafer plane gap<br />
* Technical Note<br />
** Gabriel to start drafting a procedure for developing electric fields maps in CST starting from ME models and implementing them in GPT<br />
** Max to coordinate the procedure writing with Gabriel and with Alicia to capture steps for model validation with beam-based measurements, and with full injector GPT model<br />
<br />
==<br />==<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_14_2024&diff=30644Feb 14 20242024-02-15T14:08:00Z<p>Chgarcia: /* Path forward, conclusions */</p>
<hr />
<div>==From last time==<br />
<br />
* Plan A is the 16°/30° design. We are going to start the design/fabrication process to quickly get a practice part and go through all the steps.<br />
* Alicia's GPT simulations of the injector with Max's distributions indicate all models from 15 to 18 degrees should be manageable. Higher Pierce angles (shorter focal lengths) give a large beam size in the first lens and give high transmission loss at apertures, but the latter is because everything has so far been simulated with the same lens strengths. Max and Alicia will continue this work to re-match the optics for each case to see if the whole system of gun + 1 or 2 lenses actually differs. These studies may identify a suitable Plan B geometry and tell us how much deviation from the nominal geometry can be tolerated.<br />
* Meeting with Keith on Friday to get the ME design started.<br />
* Presentation at the upcoming B-Team meeting (2/13/24) about the strategy followed to solve the R30-3 focusing problem. Carlos will make some brief introductory remarks; Max and Alicia will decide to divide the rest of the work as it makes sense.[[media:R30-4 gun plan for BTeam meeting February 13 2024.pdf|Presentation can be found here]]<br />
<br />
==Discussion==<br />
<br />
* ME design<br />
** Keith Harding attended the meeting. He talked to Vince and both developed a plan to control the hole size as best as possible per design.<br />
**# Keith will send Vince a draft drawing with hole diameter 0.010" smaller than per design, with a 0.002" radius.<br />
**# The shop will make two samples<br />
**# One sample will get mechanically polished per our procedure using the tumbler and diamond paste<br />
**# The hole diameter will be measured in the un-polished, and polished sample and compared. This will tell us how much the hole diameter increases after polishing<br />
**# Produce final drawing<br />
**# Fabricate final design part + 1 spare<br />
** Modeling and simulations<br />
*** Max and Carlos received the following message from Matt: "...check that your 16 degree electrode properly matches into the first solenoid set to a realistic value that puts a beam waist at the 15 degree dipole. Good news, we know what this solenoid setting is, we use it today".<br /><br />
<br />
==Path forward, conclusions==<br />
<br />
* Wrapping up simulations and forecasting simulations after measuring final piece hole size and puck recess<br />
** Alicia to optimize injector settings at 200 kV for R30-4 solution, using counter wound FX solenoids (the version which is still not fixed in regards to the middle plate).<br />
** Model injector at 180 kV for R30-4 using actual machine setting from the R28-2 run in the machine<br />
* Updates from Carlos:<br />
** Preparing for practicing polishing on available stainless pieces similar in size to the cathode Pierce front end<br /><br />
** Measuring holes size of test piece before and after polishing<br />
** Develop plan for puck test on manufactured piece for measuring wafer plane gap<br />
* Gabriel to start drafting a procedure for developing electric fields maps in CST starting from ME models and implementing them in GPT<br />
<br />
==<br />==<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_14_2024&diff=30643Feb 14 20242024-02-15T14:00:52Z<p>Chgarcia: /* Discussion */</p>
<hr />
<div>==From last time==<br />
<br />
* Plan A is the 16°/30° design. We are going to start the design/fabrication process to quickly get a practice part and go through all the steps.<br />
* Alicia's GPT simulations of the injector with Max's distributions indicate all models from 15 to 18 degrees should be manageable. Higher Pierce angles (shorter focal lengths) give a large beam size in the first lens and give high transmission loss at apertures, but the latter is because everything has so far been simulated with the same lens strengths. Max and Alicia will continue this work to re-match the optics for each case to see if the whole system of gun + 1 or 2 lenses actually differs. These studies may identify a suitable Plan B geometry and tell us how much deviation from the nominal geometry can be tolerated.<br />
* Meeting with Keith on Friday to get the ME design started.<br />
* Presentation at the upcoming B-Team meeting (2/13/24) about the strategy followed to solve the R30-3 focusing problem. Carlos will make some brief introductory remarks; Max and Alicia will decide to divide the rest of the work as it makes sense.[[media:R30-4 gun plan for BTeam meeting February 13 2024.pdf|Presentation can be found here]]<br />
<br />
==Discussion==<br />
<br />
* ME design<br />
** Keith Harding attended the meeting. He talked to Vince and both developed a plan to control the hole size as best as possible per design.<br />
**# Keith will send Vince a draft drawing with hole diameter 0.010" smaller than per design, with a 0.002" radius.<br />
**# The shop will make two samples<br />
**# One sample will get mechanically polished per our procedure using the tumbler and diamond paste<br />
**# The hole diameter will be measured in the un-polished, and polished sample and compared. This will tell us how much the hole diameter increases after polishing<br />
**# Produce final drawing<br />
**# Fabricate final design part + 1 spare<br />
** Modeling and simulations<br />
*** Max and Carlos received the following message from Matt: "...check that your 16 degree electrode properly matches into the first solenoid set to a realistic value that puts a beam waist at the 15 degree dipole. Good news, we know what this solenoid setting is, we use it today".<br /><br />
<br />
==Path forward, conclusions==<br />
<br />
* Wrapping up simulations and forecasting simulations after measuring final piece hole size and puck recess<br />
* Discuss next steps in term of:<br />
** Preparing/practicing polishing<br />
** Machining a test piece<br />
** Measuring holes size of test piece before and after polishing<br />
** Implementing puck test on manufactured piece for measuring wafer plane gap<br />
<br />
<br />
==<br />==<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_14_2024&diff=30639Feb 14 20242024-02-15T13:57:27Z<p>Chgarcia: /* Updates */</p>
<hr />
<div>==From last time==<br />
<br />
* Plan A is the 16°/30° design. We are going to start the design/fabrication process to quickly get a practice part and go through all the steps.<br />
* Alicia's GPT simulations of the injector with Max's distributions indicate all models from 15 to 18 degrees should be manageable. Higher Pierce angles (shorter focal lengths) give a large beam size in the first lens and give high transmission loss at apertures, but the latter is because everything has so far been simulated with the same lens strengths. Max and Alicia will continue this work to re-match the optics for each case to see if the whole system of gun + 1 or 2 lenses actually differs. These studies may identify a suitable Plan B geometry and tell us how much deviation from the nominal geometry can be tolerated.<br />
* Meeting with Keith on Friday to get the ME design started.<br />
* Presentation at the upcoming B-Team meeting (2/13/24) about the strategy followed to solve the R30-3 focusing problem. Carlos will make some brief introductory remarks; Max and Alicia will decide to divide the rest of the work as it makes sense.[[media:R30-4 gun plan for BTeam meeting February 13 2024.pdf|Presentation can be found here]]<br />
<br />
==Discussion==<br />
<br />
* ME design<br />
** Keith Harding attended the meeting. He talked to Vince and both developed a plan to control the hole size as best as possible per design.<br />
**# Keith will send Vince a draft drawing with hole diameter 0.010" smaller than per design, with a 0.002" radius.<br />
**# The shop will make two samples<br />
**# One sample will get mechanically polished per our procedure using the tumbler and diamond paste<br />
**# The hole diameter will be measured in the un-polished, and polished sample and compared. This will tell us how much the hole diameter increases after polishing<br />
**# Produce final drawing<br />
**# Fabricate final design part + 1 spare<br />
* Gabriel<br />
* Alicia<br />
* Carlos<br />
<br />
==Path forward, conclusions==<br />
<br />
* Wrapping up simulations and forecasting simulations after measuring final piece hole size and puck recess<br />
* Discuss next steps in term of:<br />
** Preparing/practicing polishing<br />
** Machining a test piece<br />
** Measuring holes size of test piece before and after polishing<br />
** Implementing puck test on manufactured piece for measuring wafer plane gap<br />
<br />
<br />
==<br />==<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_14_2024&diff=30637Feb 14 20242024-02-15T13:48:24Z<p>Chgarcia: /* From last time */</p>
<hr />
<div>==From last time==<br />
<br />
* Plan A is the 16°/30° design. We are going to start the design/fabrication process to quickly get a practice part and go through all the steps.<br />
* Alicia's GPT simulations of the injector with Max's distributions indicate all models from 15 to 18 degrees should be manageable. Higher Pierce angles (shorter focal lengths) give a large beam size in the first lens and give high transmission loss at apertures, but the latter is because everything has so far been simulated with the same lens strengths. Max and Alicia will continue this work to re-match the optics for each case to see if the whole system of gun + 1 or 2 lenses actually differs. These studies may identify a suitable Plan B geometry and tell us how much deviation from the nominal geometry can be tolerated.<br />
* Meeting with Keith on Friday to get the ME design started.<br />
* Presentation at the upcoming B-Team meeting (2/13/24) about the strategy followed to solve the R30-3 focusing problem. Carlos will make some brief introductory remarks; Max and Alicia will decide to divide the rest of the work as it makes sense.[[media:R30-4 gun plan for BTeam meeting February 13 2024.pdf|Presentation can be found here]]<br />
<br />
==Updates==<br />
<br />
* Max<br />
* Gabriel<br />
* Alicia<br />
* Carlos<br />
<br />
==Path forward, conclusions==<br />
<br />
* Wrapping up simulations and forecasting simulations after measuring final piece hole size and puck recess<br />
* Discuss next steps in term of:<br />
** Preparing/practicing polishing<br />
** Machining a test piece<br />
** Measuring holes size of test piece before and after polishing<br />
** Implementing puck test on manufactured piece for measuring wafer plane gap<br />
<br />
<br />
==<br />==<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=File:R30-4_gun_plan_for_BTeam_meeting_February_13_2024.pdf&diff=30636File:R30-4 gun plan for BTeam meeting February 13 2024.pdf2024-02-15T13:48:16Z<p>Chgarcia: </p>
<hr />
<div></div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_14_2024&diff=30635Feb 14 20242024-02-15T13:47:42Z<p>Chgarcia: /* From last time */</p>
<hr />
<div>== From last time ==<br />
<br />
* Plan A is the 16°/30° design. We are going to start the design/fabrication process to quickly get a practice part and go through all the steps.<br />
* Alicia's GPT simulations of the injector with Max's distributions indicate all models from 15 to 18 degrees should be manageable. Higher Pierce angles (shorter focal lengths) give a large beam size in the first lens and give high transmission loss at apertures, but the latter is because everything has so far been simulated with the same lens strengths. Max and Alicia will continue this work to re-match the optics for each case to see if the whole system of gun + 1 or 2 lenses actually differs. These studies may identify a suitable Plan B geometry and tell us how much deviation from the nominal geometry can be tolerated.<br />
* Meeting with Keith on Friday to get the ME design started.<br />
* Presentation at the upcoming B-Team meeting (2/13/24) about the strategy followed to solve the R30-3 focusing problem. Carlos will make some brief introductory remarks; Max and Alicia will decide to divide the rest of the work as it makes sense.[[media:R30-4 gun plan for BTeam meeting February 13 2024.pdf|Presentation can be found here]]<br />
<br />
==Updates==<br />
<br />
* Max<br />
* Gabriel<br />
* Alicia<br />
* Carlos<br />
<br />
==Path forward, conclusions==<br />
<br />
* Wrapping up simulations and forecasting simulations after measuring final piece hole size and puck recess<br />
* Discuss next steps in term of:<br />
** Preparing/practicing polishing<br />
** Machining a test piece<br />
** Measuring holes size of test piece before and after polishing<br />
** Implementing puck test on manufactured piece for measuring wafer plane gap<br />
<br />
<br />
==<br />==<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_7_2024&diff=30634Feb 7 20242024-02-15T13:46:28Z<p>Chgarcia: /* From last time */</p>
<hr />
<div>== From last time ==<br />
<br />
* Carlos will incorporate into the time line a potential vent and electrode swap in case of failure to HV-condition or get the beam out (by no means anticipated, but good to know how long it would take)<br />
* Max, Gabriel, and Alicia will complete simulations of:<br />
** shallow junction angle<br />
** tolerance bands around nominal values, especially cathode recess, to evaluate injector acceptance (see parameter table from last meeting).<br />
** Final checks: tilted anode, biased anode, 140 kV<br />
* Deadline to define Pierce angle: Today. Max, Alicia.<br />
* Deadline to provide Keith Harding with the chosen models (TWO Pierce angle options): Friday, February 9, 2024. Max, Gabriel.<br />
* February 13, 2024. Present before the B-Team meeting the strategy followed for arriving at the optimized Pierce angle. Max and Alicia.<br />
* [[media:Cathode front end geometrical paramters.pdf|Geometrical parameters downselect]]<br />
<br />
== Table of parameters ==<br />
<br />
{| class="wikitable" style="margin: auto;" data-mce-style="margin: auto;"<br />
|-<br />
! style="width: 170.461px;" data-mce-style="width: 170.461px;"|Parameter<br />
! style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|Unit<br />
! style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|Nominal value<br />
! style="width: 154.805px;" data-mce-style="width: 154.805px;"|Fabrication uncertainty<br />
! style="width: 108.891px;" data-mce-style="width: 108.891px;"|Simulation band<br />
! style="width: 474.5px;" data-mce-style="width: 474.5px;"|Comments<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Hole inner radius<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|6.4135<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|+/- 0.3?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|+/- 0.3<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|to edge of actual metal, as measured with caliper<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Pierce angle<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|16<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|+/- 2<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cone/sphere junction angle<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|30<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|30 -- 62<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|was 62°; smooth transition = 26.971°<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cathode recess<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0.188<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|0.05<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|0.1<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|from Keith's drawing; error may be larger for old pucks<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cathode tilt<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|+/- 0.5<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|1<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"| <br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Laser spot size (RMS)<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0.5<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|0.1<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|0.2<br />
|}<br />
<br />
==Updates==<br />
<br />
* Max, Gabriel, Alicia: Parameter variation studies. The nominal values above give good agreement with the R28 model; the smooth transition at the junction gives minimum field enhancement at the lip and has been shown not to cause problems due to the protruding edge (Sajini's design).<br />
** Pierce angles, junction angles: [[media:20240206_pierce_beamsize.pdf|Beam envelopes]] // [[media:20240206_pierce_focallength.pdf|Focal length vs. spot position]] -- no major optical difference between junction angles, just changes focal length; 16/30 model is closest to R28.<br />
** Anode tilt with nominal parameters, same angle as R30-3 (2°): [[media:20240206_anode_tilt_comparison.pdf|Beam envelopes]] // [[media:20240206 anode tilt focallength.pdf|Focal length vs. spot position]] -- worth keeping, no adverse effects, partial cancellation of downward kick<br />
** +/- 0.2 mm hole size: [[media:20240206_hole_beamsize.pdf|Beam envelopes]] // [[media:20240206_hole_focallength.pdf|Focal length vs. spot position]] -- suggest at most +/- 0.1 mm machining tolerance (final part after polishing etc.)<br />
*** Important to control. Keep radius small to reduce tolerance of longitudinal distance between edge and photocathode surface.<br />
** +/- 0.1 mm recess: [[media:20240206_recess_beamsize.pdf|Beam envelopes]] // [[media:20240206_recess_focallength.pdf|Focal length vs. spot position]] -- less-than-nominal recess gives unduly long focal length (note, variation is twice the limit from comparative stack-up drawing)<br />
*** could increase focusing (e.g., 1° more Pierce angle)<br />
*** but history indicates focal length tends to be shorter than simulated, i.e., more recess<br />
*** unlikely to be operationally problematic<br />
** 140 kV instead of 200: [[media:20240206_voltage_beamsize.pdf|Beam envelopes]] // [[media:20240206_voltage_focallength.pdf|Focal length vs. spot position]] -- less voltage focuses more, but not a big issue<br />
* Alicia:<br />
** What phase-space parameters are desirable? Simulations done with R30-4 candidate phase spaces provided by Max; these had the respective mean of x, x', y, y', and t subtracted to simplify integration of different guns into the model without having to adjust RF phases and correctors.<br />
** [[media:Comparison_R282_R304_variants_beamlinesims_20240207.pptx|Beam comparisons between R28-2 and R30-3 guns]]<br />
* Carlos: <br />
** Sent an un-polished 25 deg Pierce cathode front end to CMM to measure outer diameter and hole size. These are expected to indicate if these dimensions changed compared to a mechanically polished piece.<br />
** Keith Harding is ready to produce the drawing of the new cathode Pierce angle from end. He says a sketch with dimensions will be easier to model than receiving a step file.<br />
<br />
==Path forward, conclusions==<br />
<br />
* Plan A is the 16°/30° design. We are going to start the design/fabrication process to quickly get a practice part and go through all the steps.<br />
* Alicia's GPT simulations of the injector with Max's distributions indicate all models from 15 to 18 degrees should be manageable. Higher Pierce angles (shorter focal lengths) give a large beam size in the first lens and give high transmission loss at apertures, but the latter is because everything has so far been simulated with the same lens strengths. Max and Alicia will continue this work to re-match the optics for each case to see if the whole system of gun + 1 or 2 lenses actually differs. These studies may identify a suitable Plan B geometry and tell us how much deviation from the nominal geometry can be tolerated.<br />
* Meeting with Keith on Friday to get the ME design started.<br />
* Presentation at the upcoming B-Team meeting (2/13/24) about the strategy followed to solve the R30-3 focusing problem. Carlos will make some brief introductory remarks; Max and Alicia will decide to divide the rest of the work as it makes sense.<br />
<br />
==<br />==<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_14_2024&diff=30632Feb 14 20242024-02-14T12:46:59Z<p>Chgarcia: Created page with "== From last time == * Plan A is the 16°/30° design. We are going to start the design/fabrication process to quickly get a practice part and go through all the steps. * Ali..."</p>
<hr />
<div>== From last time ==<br />
<br />
* Plan A is the 16°/30° design. We are going to start the design/fabrication process to quickly get a practice part and go through all the steps.<br />
* Alicia's GPT simulations of the injector with Max's distributions indicate all models from 15 to 18 degrees should be manageable. Higher Pierce angles (shorter focal lengths) give a large beam size in the first lens and give high transmission loss at apertures, but the latter is because everything has so far been simulated with the same lens strengths. Max and Alicia will continue this work to re-match the optics for each case to see if the whole system of gun + 1 or 2 lenses actually differs. These studies may identify a suitable Plan B geometry and tell us how much deviation from the nominal geometry can be tolerated.<br />
* Meeting with Keith on Friday to get the ME design started.<br />
* Presentation at the upcoming B-Team meeting (2/13/24) about the strategy followed to solve the R30-3 focusing problem. Carlos will make some brief introductory remarks; Max and Alicia will decide to divide the rest of the work as it makes sense.<br />
<br />
==Updates==<br />
<br />
* Max<br />
* Gabriel<br />
* Alicia<br />
* Carlos<br />
<br />
==Path forward, conclusions==<br />
<br />
* Wrapping up simulations and forecasting simulations after measuring final piece hole size and puck recess<br />
* Discuss next steps in term of:<br />
** Preparing/practicing polishing<br />
** Machining a test piece<br />
** Measuring holes size of test piece before and after polishing<br />
** Implementing puck test on manufactured piece for measuring wafer plane gap<br />
<br />
<br />
==<br />==<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=200_kV_Polarized_Gun&diff=30631200 kV Polarized Gun2024-02-14T12:39:54Z<p>Chgarcia: </p>
<hr />
<div>* The 200 kV gun (R30-3 with spherical electrode and 18" gun HVC) was installed in CEBAF during SAD 2023.<br />
<br />
* This gun performed as designed in terms of vacuum, and high voltage: no field emission at 200 kV after conditioning with Kr to ~240 kV.<br />
* It has two problems:<br />
** The beam waist is ~ 6 cm downstream of the GaAs wafer, compared to ~ 40 cm from the Tee electrode 14" HVC R28-2 gun operated in CEBAF for years at 130 kV.<br />
** It was a not possible to obtain the laser retro-reflection.<br />
* The gun was then removed from the injector and replaced with the R28-2 gun.<br />
* The SAD 2024 links below capture the planning for fixing these problems in the R30-3 gun (which will be version R30-4) and for installing it in May 2024.<br />
<br />
<br />
==R30-4 200 kV Gun SharePoint site==<br />
[https://jeffersonlab.sharepoint.com/:f:/s/CIS/Ejp9S0WdeXtPgFm_bwwkuEAB0gEzYKg7Ci0UfKK8qQnPfQ?e=1tfGAH R30-4 200 kV SharePoint site]<br />
<br />
<br />
Contains:<br />
* Pierce cathode end piece geometry and beam parameter space table<br />
* Notes, studies, and documentation<br />
* Electrostatics and beam dynamics modeling and simulation results<br />
<br />
==R30-4 200 kV Gun SAD 2024 Planning Meetings==<br />
<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Jan_05_2024 Jan 05, 2024]<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Jan_10_2024 Jan 10,2024]<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Jan_17_2024 Jan 17, 2024]<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Jan_24_2024 Jan 24, 2024]<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Jan_30_2024 Jan 31, 2024]<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Feb_7_2024 Feb 7, 2024]<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Feb_14_2024 Feb 14, 2024]<br />
<br />
==R30-3 200 kV Gun SAD 2023 Installation Links==<br />
<br />
* ATLIS => https://tasklists.jlab.org/atlis/tasks/108541<br />
* Marcy's Gantt chart goes here => https://jeffersonlab-my.sharepoint.com/:x:/g/personal/marcy_jlab_org/EUe-xbLpNR1IsV28fyi20FUBC4bUllOnMnAYlXemA7C82Q<br />
* List of photocathodes at end of Phase 1 (5/10/2021) - https://logbooks.jlab.org/entry/3876517<br />
<br />
==R30-3 200 kV Gun SAD 2023 Planning Meetings==<br />
<br />
* Feb 20, 2023 => * Carlos SAD schedule [[Media:Gun swap planning 1 week before and 1 week after SAD start.pptx]]<br />
* Feb 02, 2022 => [[Feb 2, 2022 - Group meeting]] - Group meeting + 200 kV gun<br />
* Jan 26, 2022 => [[200 kV Gun - Jan 26, 2022]]<br />
<br />
==Links==<br />
<br />
* [https://wiki.jlab.org/ciswiki/index.php/18%22_Photogun_ala_GTS Carlos 18" Gun Page]<br />
* Gun Anode - Carlos's update https://wiki.jlab.org/ciswiki/index.php/Anode</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=200_kV_Polarized_Gun&diff=30630200 kV Polarized Gun2024-02-14T12:39:07Z<p>Chgarcia: </p>
<hr />
<div>* The 200 kV gun (R30-3 with spherical electrode and 18" gun HVC) was installed in CEBAF during SAD 2023.<br />
<br />
* This gun performed as designed in terms of vacuum, and high voltage: no field emission at 200 kV after conditioning with Kr to ~240 kV.<br />
* It has two problems:<br />
** The beam waist is ~ 6 cm downstream of the GaAs wafer, compared to ~ 40 cm from the Tee electrode 14" HVC R28-2 gun operated in CEBAF for years at 130 kV.<br />
** It was a not possible to obtain the laser retro-reflection.<br />
* The gun was then removed from the injector and replaced with the R28-2 gun.<br />
* The SAD 2024 links below capture the planning for fixing these problems in the R30-3 gun (which will be version R30-4) and for installing it in May 2024.<br />
<br />
<br />
==R30-4 200 kV Gun SharePoint site==<br />
[https://jeffersonlab.sharepoint.com/:f:/s/CIS/Ejp9S0WdeXtPgFm_bwwkuEAB0gEzYKg7Ci0UfKK8qQnPfQ?e=1tfGAH R30-4 200 kV SharePoint site]<br />
<br />
<br />
Contains:<br />
* Pierce cathode end piece geometry and beam parameter space table<br />
* Notes, studies, and documentation<br />
* Electrostatics and beam dynamics modeling and simulation results<br />
<br />
==R30-4 200 kV Gun SAD 2024 Planning Meetings==<br />
<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Jan_05_2024 Jan 05, 2024]<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Jan_10_2024 Jan 10,2024]<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Jan_17_2024 Jan 17, 2024]<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Jan_24_2024 Jan 24, 2024]<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Jan_30_2024 Jan 31, 2024]<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Feb_7_2024 Feb 7, 2024]<br />
* >[https://wiki.jlab.org/ciswiki/index.php/Feb_14_2024 Feb 7, 2024]<br />
<br />
==R30-3 200 kV Gun SAD 2023 Installation Links==<br />
<br />
* ATLIS => https://tasklists.jlab.org/atlis/tasks/108541<br />
* Marcy's Gantt chart goes here => https://jeffersonlab-my.sharepoint.com/:x:/g/personal/marcy_jlab_org/EUe-xbLpNR1IsV28fyi20FUBC4bUllOnMnAYlXemA7C82Q<br />
* List of photocathodes at end of Phase 1 (5/10/2021) - https://logbooks.jlab.org/entry/3876517<br />
<br />
==R30-3 200 kV Gun SAD 2023 Planning Meetings==<br />
<br />
* Feb 20, 2023 => * Carlos SAD schedule [[Media:Gun swap planning 1 week before and 1 week after SAD start.pptx]]<br />
* Feb 02, 2022 => [[Feb 2, 2022 - Group meeting]] - Group meeting + 200 kV gun<br />
* Jan 26, 2022 => [[200 kV Gun - Jan 26, 2022]]<br />
<br />
==Links==<br />
<br />
* [https://wiki.jlab.org/ciswiki/index.php/18%22_Photogun_ala_GTS Carlos 18" Gun Page]<br />
* Gun Anode - Carlos's update https://wiki.jlab.org/ciswiki/index.php/Anode</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=File:Comparison_R282_R304_variants_beamlinesims_20240207.pptx&diff=30618File:Comparison R282 R304 variants beamlinesims 20240207.pptx2024-02-07T13:45:43Z<p>Chgarcia: </p>
<hr />
<div></div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_7_2024&diff=30617Feb 7 20242024-02-07T13:45:13Z<p>Chgarcia: /* Updates */</p>
<hr />
<div>== From last time ==<br />
<br />
* Carlos will incorporate into the time line a potential vent and electrode swap in case of failure to HV-condition or get the beam out (by no means anticipated, but good to know how long it would take)<br />
* Max, Gabriel, and Alicia will complete simulations of:<br />
** shallow junction angle<br />
** tolerance bands around nominal values, especially cathode recess, to evaluate injector acceptance (see parameter table from last meeting).<br />
** Final checks: tilted anode, biased anode, 140 kV<br />
* Deadline to define Pierce angle: Today. Max, Alicia.<br />
* Deadline to provide Keith Harding with the chosen models (TWO Pierce angle options): Friday, February 9, 2024. Max, Gabriel.<br />
* February 13, 2024. Present before the B-Team meeting the strategy followed for arriving at the optimized Pierce angle. Max and Alicia.<br />
* [[media:Cathode front end geometrical paramters.pdf|Geometrical parameters downselect]]<br />
<br />
<br />
== Table of parameters ==<br />
<br />
{| class="wikitable" style="margin: auto;" data-mce-style="margin: auto;"<br />
|-<br />
! style="width: 170.461px;" data-mce-style="width: 170.461px;"|Parameter<br />
! style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|Unit<br />
! style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|Nominal value<br />
! style="width: 154.805px;" data-mce-style="width: 154.805px;"|Fabrication uncertainty<br />
! style="width: 108.891px;" data-mce-style="width: 108.891px;"|Simulation band<br />
! style="width: 474.5px;" data-mce-style="width: 474.5px;"|Comments<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Hole inner radius<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|6.4135<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|+/- 0.3?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|+/- 0.3<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|to edge of actual metal, as measured with caliper<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Pierce angle<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|16<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|+/- 2<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cone/sphere junction angle<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|30<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|30 -- 62<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|was 62°; smooth transition = 26.971°<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cathode recess<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0.188<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|0.05<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|0.1<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|from Keith's drawing; error may be larger for old pucks<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cathode tilt<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|+/- 0.5<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|1<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"| <br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Laser spot size (RMS)<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0.5<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|0.1<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|0.2<br />
|}<br />
<br />
==Updates==<br />
<br />
* Max, Gabriel, Alicia: Parameter variation studies. The nominal values above give good agreement with the R28 model; the smooth transition at the junction gives minimum field enhancement at the lip and has been shown not to cause problems due to the protruding edge (Sajini's design).<br />
** Pierce angles, junction angles: [[media:20240206_pierce_beamsize.pdf|Beam envelopes]] // [[media:20240206_pierce_focallength.pdf|Focal length vs. spot position]] -- no major optical difference between junction angles, just changes focal length; 16/30 model is closest to R28.<br />
** Anode tilt with nominal parameters, same angle as R30-3 (2°): [[media:20240206_anode_tilt_comparison.pdf|Beam envelopes]] // [[media:20240206 anode tilt focallength.pdf|Focal length vs. spot position]] -- worth keeping, no adverse effects, partial cancellation of downward kick<br />
** +/- 0.2 mm hole size: [[media:20240206_hole_beamsize.pdf|Beam envelopes]] // [[media:20240206_hole_focallength.pdf|Focal length vs. spot position]] -- suggest at most +/- 0.1 mm machining tolerance (final part after polishing etc.)<br />
*** Important to control. Keep radius small to reduce tolerance of longitudinal distance between edge and photocathode surface.<br />
** +/- 0.1 mm recess: [[media:20240206_recess_beamsize.pdf|Beam envelopes]] // [[media:20240206_recess_focallength.pdf|Focal length vs. spot position]] -- less-than-nominal recess gives unduly long focal length (note, variation is twice the limit from comparative stack-up drawing)<br />
*** could increase focusing (e.g., 1° more Pierce angle)<br />
*** but history indicates focal length tends to be shorter than simulated, i.e., more recess<br />
*** unlikely to be operationally problematic<br />
** 140 kV instead of 200: [[media:20240206_voltage_beamsize.pdf|Beam envelopes]] // [[media:20240206_voltage_focallength.pdf|Focal length vs. spot position]] -- less voltage focuses more, but not a big issue<br />
* Alicia:<br />
** What phase-space parameters are desirable? (simulations done with R30-4 candidate phase spaces)<br />
** [[media:Comparison_R282_R304_variants_beamlinesims_20240207.pptx|Beam comparisons between R28-2 and R30-3 guns]]<br />
* Carlos: <br />
** Sent an un-polished 25 deg Pierce cathode front end to CMM to measure outer diameter and hole size. These are expected to indicate if these dimensions changed compared to a mechanically polished piece.<br />
** Keith Harding is ready to produce the drawing of the new cathode Pierce angle from end. He says a sketch with dimensions will be easier to model than receiving a step file.<br />
<br />
==Path forward, conclusions==<br />
<br />
* Max, Alicia: Present at the upcoming Team meeting (2/13/24) strategy followed to solve the R30-3 focusing problem?<br />
*<br />
<br />
==<br />==<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_7_2024&diff=30615Feb 7 20242024-02-07T13:42:12Z<p>Chgarcia: /* Updates */</p>
<hr />
<div>== From last time ==<br />
<br />
* Carlos will incorporate into the time line a potential vent and electrode swap in case of failure to HV-condition or get the beam out (by no means anticipated, but good to know how long it would take)<br />
* Max, Gabriel, and Alicia will complete simulations of:<br />
** shallow junction angle<br />
** tolerance bands around nominal values, especially cathode recess, to evaluate injector acceptance (see parameter table from last meeting).<br />
** Final checks: tilted anode, biased anode, 140 kV<br />
* Deadline to define Pierce angle: Today. Max, Alicia.<br />
* Deadline to provide Keith Harding with the chosen models (TWO Pierce angle options): Friday, February 9, 2024. Max, Gabriel.<br />
* February 13, 2024. Present before the B-Team meeting the strategy followed for arriving at the optimized Pierce angle. Max and Alicia.<br />
* [[media:Cathode front end geometrical paramters.pdf|Geometrical parameters downselect]]<br />
<br />
<br />
== Table of parameters ==<br />
<br />
{| class="wikitable" style="margin: auto;" data-mce-style="margin: auto;"<br />
|-<br />
! style="width: 170.461px;" data-mce-style="width: 170.461px;"|Parameter<br />
! style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|Unit<br />
! style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|Nominal value<br />
! style="width: 154.805px;" data-mce-style="width: 154.805px;"|Fabrication uncertainty<br />
! style="width: 108.891px;" data-mce-style="width: 108.891px;"|Simulation band<br />
! style="width: 474.5px;" data-mce-style="width: 474.5px;"|Comments<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Hole inner radius<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|6.4135<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|+/- 0.3?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|+/- 0.3<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|to edge of actual metal, as measured with caliper<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Pierce angle<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|16<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|+/- 2<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cone/sphere junction angle<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|30<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|30 -- 62<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|was 62°; smooth transition = 26.971°<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cathode recess<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0.188<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|0.05<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|0.1<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|from Keith's drawing; error may be larger for old pucks<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cathode tilt<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|+/- 0.5<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|1<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"| <br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Laser spot size (RMS)<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0.5<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|0.1<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|0.2<br />
|}<br />
<br />
==Updates==<br />
<br />
* Max, Gabriel, Alicia: Parameter variation studies. The nominal values above give good agreement with the R28 model; the smooth transition at the junction gives minimum field enhancement at the lip and has been shown not to cause problems due to the protruding edge (Sajini's design).<br />
** Pierce angles, junction angles: [[media:20240206_pierce_beamsize.pdf|Beam envelopes]] // [[media:20240206_pierce_focallength.pdf|Focal length vs. spot position]] -- no major optical difference between junction angles, just changes focal length; 16/30 model is closest to R28.<br />
** Anode tilt with nominal parameters, same angle as R30-3 (2°): [[media:20240206_anode_tilt_comparison.pdf|Beam envelopes]] // [[media:20240206 anode tilt focallength.pdf|Focal length vs. spot position]] -- worth keeping, no adverse effects, partial cancellation of downward kick<br />
** +/- 0.2 mm hole size: [[media:20240206_hole_beamsize.pdf|Beam envelopes]] // [[media:20240206_hole_focallength.pdf|Focal length vs. spot position]] -- suggest at most +/- 0.1 mm machining tolerance (final part after polishing etc.)<br />
*** Important to control. Keep radius small to reduce tolerance of longitudinal distance between edge and photocathode surface.<br />
** +/- 0.1 mm recess: [[media:20240206_recess_beamsize.pdf|Beam envelopes]] // [[media:20240206_recess_focallength.pdf|Focal length vs. spot position]] -- less-than-nominal recess gives unduly long focal length (note, variation is twice the limit from comparative stack-up drawing)<br />
*** could increase focusing (e.g., 1° more Pierce angle)<br />
*** but history indicates focal length tends to be shorter than simulated, i.e., more recess<br />
*** unlikely to be operationally problematic<br />
** 140 kV instead of 200: [[media:20240206_voltage_beamsize.pdf|Beam envelopes]] // [[media:20240206_voltage_focallength.pdf|Focal length vs. spot position]] -- less voltage focuses more, but not a big issue<br />
* Alicia:<br />
** What phase-space parameters are desirable? (simulations done with R30-4 candidate phase spaces)<br />
** <br />
* Carlos: <br />
** Sent an un-polished 25 deg Pierce cathode front end to CMM to measure outer diameter and hole size. These are expected to indicate if these dimensions changed compared to a mechanically polished piece.<br />
** Keith Harding is ready to produce the drawing of the new cathode Pierce angle from end. He says a sketch with dimensions will be easier to model than receiving a step file.<br />
<br />
==Path forward, conclusions==<br />
<br />
* Max, Alicia: Present at the upcoming Team meeting (2/13/24) strategy followed to solve the R30-3 focusing problem?<br />
*<br />
<br />
==<br />==<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_7_2024&diff=30599Feb 7 20242024-02-06T14:41:19Z<p>Chgarcia: /* Path forward, conclusions */</p>
<hr />
<div>== From last time ==<br />
<br />
* Carlos will incorporate into the time line a potential vent and electrode swap in case of failure to HV-condition or get the beam out (by no means anticipated, but good to know how long it would take)<br />
* Max, Gabriel, and Alicia will complete simulations of:<br />
** shallow junction angle<br />
** tolerance bands around nominal values, especially cathode recess, to evaluate injector acceptance (see parameter table from last meeting).<br />
** Final checks: tilted anode, biased anode, 140 kV<br />
* Deadline to define Pierce angle: Today. Max, Alicia.<br />
* Deadline to provide Keith Harding with the chosen models (TWO Pierce angle options): Friday, February 9, 2024. Max, Gabriel.<br />
* February 13, 2024. Present before the B-Team meeting the strategy followed for arriving at the optimized Pierce angle. Max and Alicia.<br />
* [[media:Cathode front end geometrical paramters.pdf|Geometrical parameters downselect]]<br />
<br />
<br />
== Table of parameters ==<br />
<br />
{| class="wikitable" style="margin: auto;" data-mce-style="margin: auto;"<br />
|-<br />
! style="width: 170.461px;" data-mce-style="width: 170.461px;"|Parameter<br />
! style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|Unit<br />
! style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|Nominal value<br />
! style="width: 154.805px;" data-mce-style="width: 154.805px;"|Fabrication uncertainty<br />
! style="width: 108.891px;" data-mce-style="width: 108.891px;"|Simulation band<br />
! style="width: 474.5px;" data-mce-style="width: 474.5px;"|Comments<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Hole inner radius<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|6.4135<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|+/- 0.3?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|+/- 0.3<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|to edge of actual metal, as measured with caliper<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Pierce angle<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|16<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|+/- 2<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cone/sphere junction angle<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|30<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|30 -- 62<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|was 62°; smooth transition = 26.971°<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cathode recess<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0.188<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|0.05<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|0.1<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|from Keith's drawing; error may be larger for old pucks<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cathode tilt<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|+/- 0.5<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|1<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"| <br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Laser spot size (RMS)<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0.5<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|0.1<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|0.2<br />
|}<br />
<br />
* Add CST/GPT comparison between +/- values here<br />
<br />
==Updates==<br />
<br />
* Max, Gabriel, Alicia: The nominal values above give good agreement with the R28 model; the smooth transition at the junction gives minimum field enhancement at the lip and has been shown not to cause problems due to the protruding edge (Sajini's design).<br />
* Alicia: What phase-space parameters are desirable? (simulations done with R30-4 candidate phase spaces)<br />
* Carlos: <br />
** Sent an un-polished 25 deg Pierce cathode front end to CMM to measure outer diameter and hole size. These are expected to indicate if these dimensions changed compared to a mechanically polished piece.<br />
** Keith Harding is ready to produce the drawing of the new cathode Pierce angle from end. He says a sketch with dimensions will be easier to model than receiving a step file.<br />
<br />
==Path forward, conclusions==<br />
<br />
* Max, Alicia: Present at the upcoming Team meeting (2/13/24) strategy followed to solve the R30-3 focusing problem?<br />
*<br />
<br />
==<br />==<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_7_2024&diff=30598Feb 7 20242024-02-06T14:38:43Z<p>Chgarcia: /* Updates */</p>
<hr />
<div>== From last time ==<br />
<br />
* Carlos will incorporate into the time line a potential vent and electrode swap in case of failure to HV-condition or get the beam out (by no means anticipated, but good to know how long it would take)<br />
* Max, Gabriel, and Alicia will complete simulations of:<br />
** shallow junction angle<br />
** tolerance bands around nominal values, especially cathode recess, to evaluate injector acceptance (see parameter table from last meeting).<br />
** Final checks: tilted anode, biased anode, 140 kV<br />
* Deadline to define Pierce angle: Today. Max, Alicia.<br />
* Deadline to provide Keith Harding with the chosen models (TWO Pierce angle options): Friday, February 9, 2024. Max, Gabriel.<br />
* February 13, 2024. Present before the B-Team meeting the strategy followed for arriving at the optimized Pierce angle. Max and Alicia.<br />
* [[media:Cathode front end geometrical paramters.pdf|Geometrical parameters downselect]]<br />
<br />
<br />
== Table of parameters ==<br />
<br />
{| class="wikitable" style="margin: auto;" data-mce-style="margin: auto;"<br />
|-<br />
! style="width: 170.461px;" data-mce-style="width: 170.461px;"|Parameter<br />
! style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|Unit<br />
! style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|Nominal value<br />
! style="width: 154.805px;" data-mce-style="width: 154.805px;"|Fabrication uncertainty<br />
! style="width: 108.891px;" data-mce-style="width: 108.891px;"|Simulation band<br />
! style="width: 474.5px;" data-mce-style="width: 474.5px;"|Comments<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Hole inner radius<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|6.4135<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|+/- 0.3?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|+/- 0.3<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|to edge of actual metal, as measured with caliper<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Pierce angle<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|16<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|+/- 2<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cone/sphere junction angle<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|30<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|30 -- 62<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|was 62°; smooth transition = 26.971°<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cathode recess<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0.188<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|0.05<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|0.1<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|from Keith's drawing; error may be larger for old pucks<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cathode tilt<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|+/- 0.5<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|1<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"| <br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Laser spot size (RMS)<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0.5<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|0.1<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|0.2<br />
|}<br />
<br />
* Add CST/GPT comparison between +/- values here<br />
<br />
==Updates==<br />
<br />
* Max, Gabriel, Alicia: The nominal values above give good agreement with the R28 model; the smooth transition at the junction gives minimum field enhancement at the lip and has been shown not to cause problems due to the protruding edge (Sajini's design).<br />
* Alicia: What phase-space parameters are desirable? (simulations done with R30-4 candidate phase spaces)<br />
* Carlos: <br />
** Sent an un-polished 25 deg Pierce cathode front end to CMM to measure outer diameter and hole size. These are expected to indicate if these dimensions changed compared to a mechanically polished piece.<br />
** Keith Harding is ready to produce the drawing of the new cathode Pierce angle from end. He says a sketch with dimensions will be easier to model than receiving a step file.<br />
<br />
== Path forward, conclusions ==<br />
*<br />
*<br />
<br />
==<br />==<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Feb_7_2024&diff=30597Feb 7 20242024-02-06T14:34:33Z<p>Chgarcia: /* Path forward, conclusions */</p>
<hr />
<div>== From last time ==<br />
<br />
* Carlos will incorporate into the time line a potential vent and electrode swap in case of failure to HV-condition or get the beam out (by no means anticipated, but good to know how long it would take)<br />
* Max, Gabriel, and Alicia will complete simulations of:<br />
** shallow junction angle<br />
** tolerance bands around nominal values, especially cathode recess, to evaluate injector acceptance (see parameter table from last meeting).<br />
** Final checks: tilted anode, biased anode, 140 kV<br />
* Deadline to define Pierce angle: Today. Max, Alicia.<br />
* Deadline to provide Keith Harding with the chosen models (TWO Pierce angle options): Friday, February 9, 2024. Max, Gabriel.<br />
* February 13, 2024. Present before the B-Team meeting the strategy followed for arriving at the optimized Pierce angle. Max and Alicia.<br />
* [[media:Cathode front end geometrical paramters.pdf|Geometrical parameters downselect]]<br />
<br />
<br />
== Table of parameters ==<br />
<br />
{| class="wikitable" style="margin: auto;" data-mce-style="margin: auto;"<br />
|-<br />
! style="width: 170.461px;" data-mce-style="width: 170.461px;"|Parameter<br />
! style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|Unit<br />
! style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|Nominal value<br />
! style="width: 154.805px;" data-mce-style="width: 154.805px;"|Fabrication uncertainty<br />
! style="width: 108.891px;" data-mce-style="width: 108.891px;"|Simulation band<br />
! style="width: 474.5px;" data-mce-style="width: 474.5px;"|Comments<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Hole inner radius<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|6.4135<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|+/- 0.3?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|+/- 0.3<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|to edge of actual metal, as measured with caliper<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Pierce angle<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|16<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|+/- 2<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cone/sphere junction angle<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|30<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|30 -- 62<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|was 62°; smooth transition = 26.971°<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cathode recess<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0.188<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|0.05<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|0.1<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|from Keith's drawing; error may be larger for old pucks<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cathode tilt<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|+/- 0.5<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|1<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"| <br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Laser spot size (RMS)<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0.5<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|0.1<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|0.2<br />
|}<br />
<br />
* Add CST/GPT comparison between +/- values here<br />
<br />
== Updates ==<br />
<br />
* Max, Gabriel, Alicia: The nominal values above give good agreement with the R28 model; the smooth transition at the junction gives minimum field enhancement at the lip and has been shown not to cause problems due to the protruding edge (Sajini's design).<br />
* Alicia: What phase-space parameters are desirable? (simulations done with R30-4 candidate phase spaces)<br />
<br />
== Path forward, conclusions ==<br />
*<br />
*<br />
<br />
==<br />==<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=File:Cathode_front_end_geometrical_paramters.pdf&diff=30593File:Cathode front end geometrical paramters.pdf2024-02-05T19:09:47Z<p>Chgarcia: </p>
<hr />
<div></div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Jan_30_2024&diff=30592Jan 30 20242024-02-05T19:09:12Z<p>Chgarcia: /* Conclusions, path forward */</p>
<hr />
<div>Actually, Jan 31.<br />
<br />
==Action items from last time==<br />
<br />
* Carlos will develop a high-level timeline for the rest of the project.<br />
* Now that the simulation models are working well, Max and Gabriel will optimize<br />
** the Pierce angle to give R28-like optics as a baseline and<br />
** the junction angle to allow for a larger lip radius, and less field enhancement. Carlos does not insist on the steep angle of R30-3, it can be a smooth transition.<br />
* We will make two electrodes to have a spare; one can consider making two different shapes as a contingency plan. Carlos will ask Keith to join the meetings.<br />
* Max will consolidate the set of field maps for apples/apples comparison in Alicia's injector model. Alicia will make a comparison between the updated R28, R30-3, and R30-4 models and work toward defining an acceptance band for phase-space parameters at the match point.<br /><br />
<br />
==Updates and discussion==<br />
<br />
* Link to schedule Sharepoint[https://jeffersonlab.sharepoint.com/:x:/s/CIS/EVjEdeP3E7dJv2HtHGZh-EIBEox3TAsKm-dWNTSKGEitsg?e=3ZKhzy Link to schedule in Sharepoint]<br />
* Keith Harding reports it will take him ~ 3 days to modify the existing R30-3 Pierce front-end piece and make TWO new models per Max's design. Carlos told Keith the following parameters will change from the original R30-3 drawing:<br /><br />
** Hole diameter<br />
** Pierce angle<br />
** Junction angle<br />
** Lip radius<br />
* Carlos sent the barrel polishing technote to Jessica and Chris Dreyfuss (he is in charge of the SRF tumbler polisher). The three met and discussed a plan to practice polishing a test piece to be ready when the actual pieces come from the machine shop.<br />
* Max and Gabriel: CST model gives believable results, no remaining mysteries between CST and Poisson. Simulation results for different parameters...<br />
** [[media:20240130_gun_candidates_comparison.pdf|Beam envelopes for 15,16,17,18 degrees Pierce angle]]<br />
** [[media:20240130_largegauss_aberration_comparison.pdf|Focal length vs spot position]]<br />
* Some more data from large-active-area R28 test at 200 kV:<br />
** Applied beam-based BPM linearity correction<br />
** Zero-corrected BPM signals to symmetry axes of gun kick<br />
** [[media:20240130_uitf_r28_bpm_angles.pdf|Interpolated beam angles]]<br />
** [[media:20240130_r28_uitf_vs_gpt.pdf|Beam angles UITF vs. GPT]]<br />
** [[media:20240130_uitf_r28_bpms.pdf|Extrapolated rays including solenoid data]]<br />
** Angle from solenoid measurement sensitive to small model errors, but beam position in reasonable agreement<br />
** Measured aberration in qualitative agreement with model, albeit focal length shorter overall. Focal length was longer in previous runs, so possibly due to different cathode recess with this puck. Can probably adjust the model to make data agree.<br />
* Alicia has performed [[media:20240131_Comparison_R282_R303_R304_variants_sims_z0.19.pptx|GPT simulations]] with the updated R28 and R30-4 candidate field maps.<br />
<br />
==Conclusions, path forward==<br />
<br />
* No showstoppers identified, reasonable confidence in models established.<br />
* Time line does not leave enough room for a bake+HV test on the bench but has plenty of safety margin otherwise.<br />
** Carlos will incorporate into the time line a potential vent and electrode swap in case of failure to HV-condition or get the beam out (by no means anticipated, but good to know how long it would take)<br />
* By next meeting, Max, Gabriel, and Alicia will complete simulations of:<br />
** shallow junction angle<br />
** tolerance bands around nominal values, especially cathode recess, to evaluate injector acceptance (see parameter table from last meeting).<br />
** Final checks: tilted anode, biased anode, 140 kV<br />
* Deadline to define Pierce angle: Wednesday, February 7, 2024. Max, Alicia.<br />
* Deadline to provide Keith Harding with the chosen models (TWO Pierce angle options): Friday, February 9, 2024. Max, Gabriel.<br />
* February 13, 2024. Present before the B-Team meeting the strategy followed for arriving at the optimized Pierce angle. Max and Alicia.<br />
* [[media:Cathode front end geometrical paramters.pdf|Geometrical parameters downselect]]<br />
<br />
==<br />==<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Jan_30_2024&diff=30569Jan 30 20242024-01-30T16:07:29Z<p>Chgarcia: /* Updates and discussion */</p>
<hr />
<div>==Action items from last time==<br />
<br />
* Carlos will develop a high-level timeline for the rest of the project.<br />
* Now that the simulation models are working well, Max and Gabriel will optimize<br />
** the Pierce angle to give R28-like optics as a baseline and<br />
** the junction angle to allow for a larger lip radius, and less field enhancement. Carlos does not insist on the steep angle of R30-3, it can be a smooth transition.<br />
* We will make two electrodes to have a spare; one can consider making two different shapes as a contingency plan. Carlos will ask Keith to join the meetings.<br />
* Max will consolidate the set of field maps for apples/apples comparison in Alicia's injector model. Alicia will make a comparison between the updated R28, R30-3, and R30-4 models and work toward defining an acceptance band for phase-space parameters at the match point.<br /><br />
<br />
==Updates and discussion==<br />
<br />
* Link to schedule Sharepoint[https://jeffersonlab.sharepoint.com/:x:/s/CIS/EVjEdeP3E7dJv2HtHGZh-EIBEox3TAsKm-dWNTSKGEitsg?e=3ZKhzy Link to schedule in Sharepoint]<br />
* Keith Harding reports it will take him ~ 3 days to modify the existing R30-3 Pierce front-end piece and make TWO new models per Max's design. Carlos told Keith the following parameters will change from the original R30-3 drawing:<br /><br />
** Hole diameter<br />
** Pierce angle<br />
** Junction angle<br />
** Lip radius<br />
* Carlos sent the barrel polishing technote to Jessica and Chris Dreyfuss (he is in charge of the SRF tumbler polisher). The three met and discussed a plan to practice polishing a test piece to be ready when the actual pieces come from the machine shop.<br />
<br />
==Conclusions, path forward==<br />
<br />
* Deadline to define Pierce angle: Wednesday, February 7, 2024.Max, Alicia.<br />
* Deadline to provide Keith Harding with the chosen models (TWO Pierce angle options): Friday, February 9, 2024.Max, Gabriel:<br />
* February 13, 2024. Present before the B-Team meeting the strategy followed for arriving at the optimized Pierce angle. Max and Alicia.<br />
* Enter here additional input from the meeting<br />
<br />
==<br />==<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Jan_30_2024&diff=30568Jan 30 20242024-01-30T15:57:11Z<p>Chgarcia: </p>
<hr />
<div>==Action items from last time==<br />
<br />
* Carlos will develop a high-level timeline for the rest of the project.<br />
* Now that the simulation models are working well, Max and Gabriel will optimize<br />
** the Pierce angle to give R28-like optics as a baseline and<br />
** the junction angle to allow for a larger lip radius, and less field enhancement. Carlos does not insist on the steep angle of R30-3, it can be a smooth transition.<br />
* We will make two electrodes to have a spare; one can consider making two different shapes as a contingency plan. Carlos will ask Keith to join the meetings.<br />
* Max will consolidate the set of field maps for apples/apples comparison in Alicia's injector model. Alicia will make a comparison between the updated R28, R30-3, and R30-4 models and work toward defining an acceptance band for phase-space parameters at the match point.<br /><br />
<br />
==Updates and discussion==<br />
<br />
* Link to schedule Sharepoint[https://jeffersonlab.sharepoint.com/:x:/s/CIS/EVjEdeP3E7dJv2HtHGZh-EIBEox3TAsKm-dWNTSKGEitsg?e=3ZKhzy Link to schedule in Sharepoint]<br />
* Keith Harding reports it will take him ~ 3 days to modify the existing R30-3 Pierce front-end piece and make TWO new models per Max's design. Carlos told Keith the following parameters will change from the original R30-3 drawing:<br /><br />
** Hole diameter<br />
** Pierce angle<br />
** Junction angle<br />
** Lip radius<br />
<br />
==Conclusions, path forward==<br />
<br />
* Deadline to define Pierce angle: Wednesday, February 7, 2024.Max, Alicia.<br />
* Deadline to provide Keith Harding with the chosen models (TWO Pierce angle options): Friday, February 9, 2024.Max, Gabriel:<br />
* February 13, 2024. Present before the B-Team meeting the strategy followed for arriving at the optimized Pierce angle. Max and Alicia.<br />
* Enter here additional input from the meeting<br />
<br />
==<br />==<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Jan_24_2024&diff=30567Jan 24 20242024-01-30T15:52:42Z<p>Chgarcia: /* Table of parameters (tentative) */</p>
<hr />
<div>==Action items from last time==<br />
<br />
* Gabriel will work w/ ME to confirm the R28 cathode insert hole size/shape, i.e. post the shop print, <br />
* Gabriel/Max will decide on prototypical R30-4 parameters like that of the R28 cathode insert (hole, cone shape, lip shape) at CEBAF, then Gabriel will generate the corresponding CST model, and Alicia will include this in her comparison with (R28 & R30 @ z=19cm optics match-point),<br />
* Gabriel will look at testing a cylindrically symmetric CST model against Max's POISSON model to confirm differences, intending to confirm that the differences are just 2-D vs. 3-D, nothing else,<br />
* Alicia will continue to develop bands of acceptance parameters at Z=19cm, where parameters refers to the beam/optics parameters acceptable/typical for the CEBAF injector (implicitly meaning up to max current),<br />
* Max and Alicia will continue to develop and experimental match-point for the purpose of comparison between measurement and model; as mentioned above a simulation match-point at Z=19cm has already been found in a drift free region after the gun,<br />
* Max will provide some sets of optics optimized cathode parameters (hole=fixed, cone shape, lip shape) to Gabriel, so he may generate a detailed CST model to explore max E-field strengths at surfaces/triple-points,<br />
* Max will take the lead to develop the table of parameters with uncertainties which will be used in the simulations (GPT/CST), these will be used to develop allowable tolerances in fabrication/assembly so we can with high likelihood end up within Alicia's acceptance bands,<br />
<br />
==Alicia==<br />
==Max and Gabriel==<br />
<br />
* Resolved discrepancy related to different definition of hole diameter: now we consistently use the dimensions from the T-cathode drawing<br />
* Correct cathode position for field map export/import relative to particle start coordinates is important; this changes with cathode recess<br />
* CST field maps tend to be unphysical close to cathode if export boundaries do not align with mesh cells, causing sensitivity to step size in exported file<br />
** The correct strategy is to start the field map exactly at the photocathode surface. Choose subvolume end point to be start point + multiple of step size to avoid confusing the exporter. In some cases, we need more decimal places than displayed by the idiotic point-picking text box; use trick to get the accurate number, e.g., start defining a cylinder from the picked point and get number from dialog box.<br />
** Then and only then, the step size makes no difference, 0.5 mm is enough.<br />
<br />
* Comparison R28, 0.18 mm recess, hole ID per drawing<br />
** CST: 73/53 cm, Poisson: 46 cm, measured at CEBAF 180 kV: 42/37 cm, measured at UITF 200 kV: 27/25 cm<br />
** difference simulation/reality may be related to recess and/or hole diameter<br />
<br />
* Comparison R30-4, 0.18 mm recess, hole ID same as R28, 15° cone, cone/sphere junction same as R30-3<br />
** Sanity check: symmetric CST model (NEG stuff and HV stalk + guard ring deleted) gives almost the same field map as Poisson, Ez within 0.2 % everywhere<br />
*** CST: 82 cm, Poisson: 78 cm<br />
*** OK, we know what we are modeling, tracking results match<br />
** Complete CST model<br />
*** CST: 92/56 cm, Poisson: 78 cm<br />
*** Too little focusing. Recommend slight increase in Pierce angle to better match R28 results; likely involves a compromise due to stronger astigmatism<br />
<br />
==Carlos==<br />
<br />
* The 25 deg Pierce cathode front end piece from the GTS spherical electrode gun (R30-1, Yan's thesis) was measured by SRF's Coordinate-Measurement Machine (CMM).<br />
* Findings:<br />
** Pierce angle design: 25 deg. Measured: 24.4 deg.<br />
** Cathode hole diameter to extrapolation of conical edge: Design: 0.432 inches = 10.97 mm. Measured: 0.467 in = 11.86 mm<br />
** Drawing and CMM findings can be found in the SharePoint folder [https://jeffersonlab.sharepoint.com/:f:/s/CIS/Eue6Nk9NNoRCqQpp4LhuaU4BdFAopufFt7xX36aZFbuETA?e=1bTSJp here]<br />
<br />
<br />
==Table of parameters (tentative)==<br />
<br />
{| class="wikitable" style="margin: auto;" data-mce-style="margin: auto;"<br />
|-<br />
! style="width: 170.461px;" data-mce-style="width: 170.461px;"|Parameter<br />
! style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|Unit<br />
! style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|Nominal value<br />
! style="width: 154.805px;" data-mce-style="width: 154.805px;"|Fabrication uncertainty<br />
! style="width: 108.891px;" data-mce-style="width: 108.891px;"|Simulation band<br />
! style="width: 474.5px;" data-mce-style="width: 474.5px;"|Comments<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Hole inner radius<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|6.4135<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|+/- 0.3?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|+/- 0.3<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|to edge of actual metal, as measured with caliper<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Pierce angle<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|15<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|+/- 2<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|likely need to increase<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cone/sphere junction angle<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|62<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|30 -- 62<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|to be decided based on field-emission concerns; smooth transition = 26.971°<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cathode recess<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0.188<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|0.05<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|0.1<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|from Keith's drawing; error may be larger for old pucks<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cathode tilt<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|+/- 0.5<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|1<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"| <br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Laser spot size (RMS)<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0.5<br />
| style="width: 154.805px;" data-mce-style="width: 154.805px;"|0.1<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|0.2<br />
|}<br />
<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]<br />
<br />
==Conclusions, path forward==<br />
<br />
* Carlos will develop a high-level time line for the rest of the project.<br />
* Now that the simulation models are working well, Max and Gabriel will optimize<br />
** the Pierce angle to give R28-like optics as a baseline and<br />
** the junction angle to allow for a larger lip radius, less field enhancement. Carlos does not insist on the steep angle of R30-3, it can be a smooth transition.<br />
* We will make two electrodes to have a spare; one can consider making two different shapes as a contingency plan. Carlos will ask Keith to join the meetings.<br />
* Max will consolidate the set of field maps for apples/apples comparison in Alicia's injector model. Alicia will make a comparison between the updated R28, R30-3, and R30-4 models and work toward defining an acceptance band for phase-space parameters at the match point.</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Jan_30_2024&diff=30566Jan 30 20242024-01-30T15:49:09Z<p>Chgarcia: /* Table of parameters (tentative) */</p>
<hr />
<div>==Action items from last time==<br />
<br />
* Carlos will develop a high-level timeline for the rest of the project.<br />
* Now that the simulation models are working well, Max and Gabriel will optimize<br />
** the Pierce angle to give R28-like optics as a baseline and<br />
** the junction angle to allow for a larger lip radius, and less field enhancement. Carlos does not insist on the steep angle of R30-3, it can be a smooth transition.<br />
* We will make two electrodes to have a spare; one can consider making two different shapes as a contingency plan. Carlos will ask Keith to join the meetings.<br />
* Max will consolidate the set of field maps for apples/apples comparison in Alicia's injector model. Alicia will make a comparison between the updated R28, R30-3, and R30-4 models and work toward defining an acceptance band for phase-space parameters at the match point.<br /><br />
<br />
==Updates and discussion==<br />
<br />
* Link to schedule Sharepoint<br />
* Keith Harding reports it will take him ~ 3 days to modify the existing R30-3 Pierce front-end piece and make TWO new models per Max's design. Carlos told Keith the following parameters will change from the original R30-3 drawing:<br /><br />
** Hole diameter<br />
** Pierce angle<br />
** Junction angle<br />
** Lip radius<br />
<br />
==Conclusions, path forward==<br />
<br />
* Deadline to define Pierce angle: Wednesday, February 7, 2024.Max, Alicia.<br />
* Deadline to provide Keith Harding with the chosen models (TWO Pierce angle options): Friday, February 9, 2024.Max, Gabriel:<br />
* February 13, 2024. Present before the B-Team meeting the strategy followed for arriving at the optimized Pierce angle. Max and Alicia.<br />
* Enter here additional input from the meeting<br />
<br />
==<br />==<br />
<br />
<br />
<br />
<br />
<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Jan_30_2024&diff=30565Jan 30 20242024-01-30T15:48:58Z<p>Chgarcia: /* */</p>
<hr />
<div>==Action items from last time==<br />
<br />
* Carlos will develop a high-level timeline for the rest of the project.<br />
* Now that the simulation models are working well, Max and Gabriel will optimize<br />
** the Pierce angle to give R28-like optics as a baseline and<br />
** the junction angle to allow for a larger lip radius, and less field enhancement. Carlos does not insist on the steep angle of R30-3, it can be a smooth transition.<br />
* We will make two electrodes to have a spare; one can consider making two different shapes as a contingency plan. Carlos will ask Keith to join the meetings.<br />
* Max will consolidate the set of field maps for apples/apples comparison in Alicia's injector model. Alicia will make a comparison between the updated R28, R30-3, and R30-4 models and work toward defining an acceptance band for phase-space parameters at the match point.<br /><br />
<br />
==Updates and discussion==<br />
<br />
* Link to schedule Sharepoint<br />
* Keith Harding reports it will take him ~ 3 days to modify the existing R30-3 Pierce front-end piece and make TWO new models per Max's design. Carlos told Keith the following parameters will change from the original R30-3 drawing:<br /><br />
** Hole diameter<br />
** Pierce angle<br />
** Junction angle<br />
** Lip radius<br />
<br />
==Conclusions, path forward==<br />
<br />
* Deadline to define Pierce angle: Wednesday, February 7, 2024.Max, Alicia.<br />
* Deadline to provide Keith Harding with the chosen models (TWO Pierce angle options): Friday, February 9, 2024.Max, Gabriel:<br />
* February 13, 2024. Present before the B-Team meeting the strategy followed for arriving at the optimized Pierce angle. Max and Alicia.<br />
* Enter here additional input from the meeting<br />
<br />
==<br />==<br />
<br />
==Table of parameters (tentative)==<br />
<br />
{| class="wikitable" style="margin: auto;" data-mce-style="margin: auto;"<br />
|-<br />
!Parameter<br />
!Unit<br />
!Nominal value<br />
!Fabrication uncertainty<br />
!Simulation band<br />
!Comments<br />
|-<br />
|Hole inner radius<br />
|mm<br />
|6.4135<br />
|+/- 0.3?<br />
|+/- 0.3<br />
|to edge of actual metal, as measured with caliper<br />
|-<br />
|Pierce angle<br />
|°<br />
|15<br />
|?<br />
|+/- 2<br />
|likely need to increase<br />
|-<br />
|Cone/sphere junction angle<br />
|°<br />
|62<br />
|?<br />
|30 -- 62<br />
|to be decided based on field-emission concerns; smooth transition = 26.971°<br />
|-<br />
|Cathode recess<br />
|mm<br />
|0.188<br />
|0.05<br />
|0.1<br />
|from Keith's drawing; error may be larger for old pucks<br />
|-<br />
|Cathode tilt<br />
|°<br />
|0<br />
|+/- 0.5<br />
|1<br />
| <br />
|-<br />
|Laser spot size (RMS)<br />
|mm<br />
|0.5<br />
|0.1<br />
|0.2<br />
|}<br />
<br />
<br />
<br />
[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Jan_30_2024&diff=30564Jan 30 20242024-01-30T15:48:27Z<p>Chgarcia: /* Table of parameters (tentative) */</p>
<hr />
<div>==Action items from last time==<br />
<br />
* Carlos will develop a high-level timeline for the rest of the project.<br />
* Now that the simulation models are working well, Max and Gabriel will optimize<br />
** the Pierce angle to give R28-like optics as a baseline and<br />
** the junction angle to allow for a larger lip radius, and less field enhancement. Carlos does not insist on the steep angle of R30-3, it can be a smooth transition.<br />
* We will make two electrodes to have a spare; one can consider making two different shapes as a contingency plan. Carlos will ask Keith to join the meetings.<br />
* Max will consolidate the set of field maps for apples/apples comparison in Alicia's injector model. Alicia will make a comparison between the updated R28, R30-3, and R30-4 models and work toward defining an acceptance band for phase-space parameters at the match point.<br /><br />
<br />
==Updates and discussion==<br />
<br />
* Link to schedule Sharepoint<br />
* Keith Harding reports it will take him ~ 3 days to modify the existing R30-3 Pierce front-end piece and make TWO new models per Max's design. Carlos told Keith the following parameters will change from the original R30-3 drawing:<br /><br />
** Hole diameter<br />
** Pierce angle<br />
** Junction angle<br />
** Lip radius<br />
<br />
==Conclusions, path forward==<br />
<br />
* Deadline to define Pierce angle: Wednesday, February 7, 2024.Max, Alicia.<br />
* Deadline to provide Keith Harding with the chosen models (TWO Pierce angle options): Friday, February 9, 2024.Max, Gabriel:<br />
* February 13, 2024. Present before the B-Team meeting the strategy followed for arriving at the optimized Pierce angle. Max and Alicia.<br />
* Enter here additional input from the meeting<br />
<br />
==<br />==<br />
==Table of parameters (tentative)==<br />
<br />
{| class="wikitable" style="margin: auto;" data-mce-style="margin: auto;"<br />
|-<br />
!Parameter<br />
!Unit<br />
!Nominal value<br />
!Fabrication uncertainty<br />
!Simulation band<br />
!Comments<br />
|-<br />
|Hole inner radius<br />
|mm<br />
|6.4135<br />
|+/- 0.3?<br />
|+/- 0.3<br />
|to edge of actual metal, as measured with caliper<br />
|-<br />
|Pierce angle<br />
|°<br />
|15<br />
|?<br />
|+/- 2<br />
|likely need to increase<br />
|-<br />
|Cone/sphere junction angle<br />
|°<br />
|62<br />
|?<br />
|30 -- 62<br />
|to be decided based on field-emission concerns; smooth transition = 26.971°<br />
|-<br />
|Cathode recess<br />
|mm<br />
|0.188<br />
|0.05<br />
|0.1<br />
|from Keith's drawing; error may be larger for old pucks<br />
|-<br />
|Cathode tilt<br />
|°<br />
|0<br />
|+/- 0.5<br />
|1<br />
| <br />
|-<br />
|Laser spot size (RMS)<br />
|mm<br />
|0.5<br />
|0.1<br />
|0.2<br />
|}<br />
<br />
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[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]</div>Chgarciahttps://wiki.jlab.org/ciswiki/index.php?title=Jan_24_2024&diff=30563Jan 24 20242024-01-30T15:46:53Z<p>Chgarcia: /* Table of parameters (tentative) */</p>
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<div>==Action items from last time==<br />
<br />
* Gabriel will work w/ ME to confirm the R28 cathode insert hole size/shape, i.e. post the shop print, <br />
* Gabriel/Max will decide on prototypical R30-4 parameters like that of the R28 cathode insert (hole, cone shape, lip shape) at CEBAF, then Gabriel will generate the corresponding CST model, and Alicia will include this in her comparison with (R28 & R30 @ z=19cm optics match-point),<br />
* Gabriel will look at testing a cylindrically symmetric CST model against Max's POISSON model to confirm differences, intending to confirm that the differences are just 2-D vs. 3-D, nothing else,<br />
* Alicia will continue to develop bands of acceptance parameters at Z=19cm, where parameters refers to the beam/optics parameters acceptable/typical for the CEBAF injector (implicitly meaning up to max current),<br />
* Max and Alicia will continue to develop and experimental match-point for the purpose of comparison between measurement and model; as mentioned above a simulation match-point at Z=19cm has already been found in a drift free region after the gun,<br />
* Max will provide some sets of optics optimized cathode parameters (hole=fixed, cone shape, lip shape) to Gabriel, so he may generate a detailed CST model to explore max E-field strengths at surfaces/triple-points,<br />
* Max will take the lead to develop the table of parameters with uncertainties which will be used in the simulations (GPT/CST), these will be used to develop allowable tolerances in fabrication/assembly so we can with high likelihood end up within Alicia's acceptance bands,<br />
<br />
==Alicia==<br />
==Max and Gabriel==<br />
<br />
* Resolved discrepancy related to different definition of hole diameter: now we consistently use the dimensions from the T-cathode drawing<br />
* Correct cathode position for field map export/import relative to particle start coordinates is important; this changes with cathode recess<br />
* CST field maps tend to be unphysical close to cathode if export boundaries do not align with mesh cells, causing sensitivity to step size in exported file<br />
** The correct strategy is to start the field map exactly at the photocathode surface. Choose subvolume end point to be start point + multiple of step size to avoid confusing the exporter. In some cases, we need more decimal places than displayed by the idiotic point-picking text box; use trick to get the accurate number, e.g., start defining a cylinder from the picked point and get number from dialog box.<br />
** Then and only then, the step size makes no difference, 0.5 mm is enough.<br />
<br />
* Comparison R28, 0.18 mm recess, hole ID per drawing<br />
** CST: 73/53 cm, Poisson: 46 cm, measured at CEBAF 180 kV: 42/37 cm, measured at UITF 200 kV: 27/25 cm<br />
** difference simulation/reality may be related to recess and/or hole diameter<br />
<br />
* Comparison R30-4, 0.18 mm recess, hole ID same as R28, 15° cone, cone/sphere junction same as R30-3<br />
** Sanity check: symmetric CST model (NEG stuff and HV stalk + guard ring deleted) gives almost the same field map as Poisson, Ez within 0.2 % everywhere<br />
*** CST: 82 cm, Poisson: 78 cm<br />
*** OK, we know what we are modeling, tracking results match<br />
** Complete CST model<br />
*** CST: 92/56 cm, Poisson: 78 cm<br />
*** Too little focusing. Recommend slight increase in Pierce angle to better match R28 results; likely involves a compromise due to stronger astigmatism<br />
<br />
==Carlos==<br />
<br />
* The 25 deg Pierce cathode front end piece from the GTS spherical electrode gun (R30-1, Yan's thesis) was measured by SRF's Coordinate-Measurement Machine (CMM).<br />
* Findings:<br />
** Pierce angle design: 25 deg. Measured: 24.4 deg.<br />
** Cathode hole diameter to extrapolation of conical edge: Design: 0.432 inches = 10.97 mm. Measured: 0.467 in = 11.86 mm<br />
** Drawing and CMM findings can be found in the SharePoint folder [https://jeffersonlab.sharepoint.com/:f:/s/CIS/Eue6Nk9NNoRCqQpp4LhuaU4BdFAopufFt7xX36aZFbuETA?e=1bTSJp here]<br />
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<br />
==Table of parameters (tentative)==<br />
<br />
{| class="wikitable" style="margin: auto;" data-mce-style="margin: auto;"<br />
|-<br />
! style="width: 170.461px;" data-mce-style="width: 170.461px;"|Parameter<br />
! style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|Unit<br />
! style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|Nominal value<br />
! style="width: 154.812px;" data-mce-style="width: 154.812px;"|Fabrication uncertainty<br />
! style="width: 108.891px;" data-mce-style="width: 108.891px;"|Simulation band<br />
! style="width: 474.5px;" data-mce-style="width: 474.5px;"|Comments<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Hole inner radius<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|6.4135<br />
| style="width: 154.812px;" data-mce-style="width: 154.812px;"|+/- 0.3?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|+/- 0.3<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|to edge of actual metal, as measured with caliper<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Pierce angle<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|15<br />
| style="width: 154.812px;" data-mce-style="width: 154.812px;"|?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|+/- 2<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|likely need to increase<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cone/sphere junction angle<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|62<br />
| style="width: 154.812px;" data-mce-style="width: 154.812px;"|?<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|30 -- 62<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|to be decided based on field-emission concerns; smooth transition = 26.971°<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cathode recess<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0.188<br />
| style="width: 154.812px;" data-mce-style="width: 154.812px;"|0.05<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|0.1<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"|from Keith's drawing; error may be larger for old pucks<br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Cathode tilt<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|°<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0<br />
| style="width: 154.812px;" data-mce-style="width: 154.812px;"|+/- 0.5<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|1<br />
| style="width: 474.5px;" data-mce-style="width: 474.5px;"| <br />
|-<br />
| style="width: 170.461px;" data-mce-style="width: 170.461px;"|Laser spot size (RMS)<br />
| style="width: 27.2188px;" data-mce-style="width: 27.2188px;"|mm<br />
| style="width: 94.9219px;" data-mce-style="width: 94.9219px;"|0.5<br />
| style="width: 154.812px;" data-mce-style="width: 154.812px;"|0.1<br />
| style="width: 108.891px;" data-mce-style="width: 108.891px;"|0.2<br />
|}<br />
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[https://wiki.jlab.org/ciswiki/index.php/200_kV_Polarized_Gun Return to 200 kV Gun page]<br />
<br />
==Conclusions, path forward==<br />
<br />
* Carlos will develop a high-level time line for the rest of the project.<br />
* Now that the simulation models are working well, Max and Gabriel will optimize<br />
** the Pierce angle to give R28-like optics as a baseline and<br />
** the junction angle to allow for a larger lip radius, less field enhancement. Carlos does not insist on the steep angle of R30-3, it can be a smooth transition.<br />
* We will make two electrodes to have a spare; one can consider making two different shapes as a contingency plan. Carlos will ask Keith to join the meetings.<br />
* Max will consolidate the set of field maps for apples/apples comparison in Alicia's injector model. Alicia will make a comparison between the updated R28, R30-3, and R30-4 models and work toward defining an acceptance band for phase-space parameters at the match point.</div>Chgarcia