Difference between revisions of "UITF Notes"
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== MeV beam time == | == MeV beam time == | ||
| − | * | + | * Test IHAM505 |
* TM beam to 703 to see RF drift (full shift) | * TM beam to 703 to see RF drift (full shift) | ||
* Verify optics setup for HKDL | * Verify optics setup for HKDL | ||
| + | ** To produce small beam at M703, first measure Twiss at 501 and then optimize beta_x with Elegant: try to make it small in the dipole AND at the harp if possible (keep the dipole from focusing) | ||
* Repeat buncher study, booster crested, 8 MeV, multiple scans per point | * Repeat buncher study, booster crested, 8 MeV, multiple scans per point | ||
| + | ** It may be interesting to do the buncher study with the 7-cell off. | ||
| + | ** This reduces microphonics impact, but optics of the low-energy beam are a problem | ||
| + | ** Crank 2-cell up? | ||
| + | * Buncher power vs. GSET | ||
| + | ** Once correct buncher power is found, measure displacement at +/- 90 degrees on K501 again | ||
| + | * Test booster off crest, scan buncher if results good | ||
== keV beam time == | == keV beam time == | ||
| Line 12: | Line 19: | ||
*** Try adjustable bias voltage source (Keithley) | *** Try adjustable bias voltage source (Keithley) | ||
* HVQE scan at different voltages. Expect different result. | * HVQE scan at different voltages. Expect different result. | ||
| − | * High current to FC2 for 12+ hours, check if drift is gone | + | * High current to FC2 for 12+ hours, check if drift is gone. Check with buncher ON and buncher OFF. |
* Look at [https://logbooks.jlab.org/entry/4022870 mains-harmonic BPM signals] as a function of parameters (buncher etc.) | * Look at [https://logbooks.jlab.org/entry/4022870 mains-harmonic BPM signals] as a function of parameters (buncher etc.) | ||
| + | * Measure bunch length upstream (chopper or Brock) | ||
| − | == | + | == Random things to change when it makes sense == |
| − | * | + | * The way MFQK403 is supposed to focus into both Aperture A4 and the booster is flawed for multiple reasons: |
| − | * | + | ** The lens would need to produce multiple waists (DP can, A4, Brock cavity, RM11), so the focal length is a compromise. But interestingly, it is the same at CEBAF. |
| + | ** The orbit needs to be very straight for the beam to make it all the way downstream, but to adjust this, we need both upstream correctors, 401A and 402, so centering in the lens at the same time is very difficult. | ||
| + | ** We should do a GPT study and play with a potential extra lens, but I would intuitively suggest something like this: | ||
| + | *** Remove Brock cavity, not needed | ||
| + | *** Add corrector between MFQK403 and A4 | ||
| + | *** I think having the beam converge slowly into the booster is good, so I like that the lens is far away. Maybe the aperture should just be closer to the booster? At the very least, put it behind the BPM so we can see where we're at. | ||
| + | * MFAK303 has a similar problem. Being single-wound, it is supposed to be equal and opposite to MFAK301, but this fixes its focal length, while it is supposed to focus in both the buncher and the dipole. This issue does not seem critical, but it could be pondered sometime. | ||
Latest revision as of 14:43, 12 November 2022
MeV beam time
- Test IHAM505
- TM beam to 703 to see RF drift (full shift)
- Verify optics setup for HKDL
- To produce small beam at M703, first measure Twiss at 501 and then optimize beta_x with Elegant: try to make it small in the dipole AND at the harp if possible (keep the dipole from focusing)
- Repeat buncher study, booster crested, 8 MeV, multiple scans per point
- It may be interesting to do the buncher study with the 7-cell off.
- This reduces microphonics impact, but optics of the low-energy beam are a problem
- Crank 2-cell up?
- Buncher power vs. GSET
- Once correct buncher power is found, measure displacement at +/- 90 degrees on K501 again
- Test booster off crest, scan buncher if results good
keV beam time
- LVQE scan at different voltages. Expect same result, provided different laser powers at same voltage give same result (avoid SCL).
- Results are different, don't know if related to instrumentation (battery resistance etc.) or physics. If it's physics:
- CST: Does thermal energy affect collection efficiency?
- Ion current? probably too low to matter
- Try adjustable bias voltage source (Keithley)
- Results are different, don't know if related to instrumentation (battery resistance etc.) or physics. If it's physics:
- HVQE scan at different voltages. Expect different result.
- High current to FC2 for 12+ hours, check if drift is gone. Check with buncher ON and buncher OFF.
- Look at mains-harmonic BPM signals as a function of parameters (buncher etc.)
- Measure bunch length upstream (chopper or Brock)
Random things to change when it makes sense
- The way MFQK403 is supposed to focus into both Aperture A4 and the booster is flawed for multiple reasons:
- The lens would need to produce multiple waists (DP can, A4, Brock cavity, RM11), so the focal length is a compromise. But interestingly, it is the same at CEBAF.
- The orbit needs to be very straight for the beam to make it all the way downstream, but to adjust this, we need both upstream correctors, 401A and 402, so centering in the lens at the same time is very difficult.
- We should do a GPT study and play with a potential extra lens, but I would intuitively suggest something like this:
- Remove Brock cavity, not needed
- Add corrector between MFQK403 and A4
- I think having the beam converge slowly into the booster is good, so I like that the lens is far away. Maybe the aperture should just be closer to the booster? At the very least, put it behind the BPM so we can see where we're at.
- MFAK303 has a similar problem. Being single-wound, it is supposed to be equal and opposite to MFAK301, but this fixes its focal length, while it is supposed to focus in both the buncher and the dipole. This issue does not seem critical, but it could be pondered sometime.