Difference between revisions of "GTS meeting 5 02 17"
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| − | == | + | == Attempted to run at 1 mA == |
# Ran for few seconds before a HV arc. QE dropped by a factor of 2. | # Ran for few seconds before a HV arc. QE dropped by a factor of 2. | ||
# Ran again for 1.5 hours with ion-precipitators on (?) before a HV arc. QE dropped by another factor of 2. | # Ran again for 1.5 hours with ion-precipitators on (?) before a HV arc. QE dropped by another factor of 2. | ||
| − | == Down Monday – Wednesday | + | == List of Tasks (Down Monday – Wednesday)== |
# Re-activate photocathode with 3 mm active area | # Re-activate photocathode with 3 mm active area | ||
# Degas dump with NEGs at 2 Amps AC on for ion pumps to take vacuum load | # Degas dump with NEGs at 2 Amps AC on for ion pumps to take vacuum load | ||
| Line 12: | Line 12: | ||
## Shukui installed ND3 filter on spare servo motor 2. We should start using this ND filter. It is now on the Tool Screen. | ## Shukui installed ND3 filter on spare servo motor 2. We should start using this ND filter. It is now on the Tool Screen. | ||
# Instrument wire scanner | # Instrument wire scanner | ||
| − | # | + | # Installed WiFi access point in GTS cave and enabled JMenu on PC using NX-Connects and Two-Factor Authentication. Then: ssh fell08, jmenu MainMenuGTS. |
# Why is Dump/FC picoammeter reading is noisy? up to 20 nA. | # Why is Dump/FC picoammeter reading is noisy? up to 20 nA. | ||
# Hi-pot VIPGT06 | # Hi-pot VIPGT06 | ||
| Line 19: | Line 19: | ||
| − | == | + | == Beam Gap Clearing == |
| − | + | *An alternative to applying electric field (bias) is removing intrinsic electric field (beam)... | |
| + | : Beam 'off' time of ~few microseconds w/ rep rate at least greater than ~100 Hz should do OK | ||
| + | :: Additional 'do something' half-wave plate within tune mode generator + User mode... | ||
| + | :: Spinning optical chopper ? | ||
| + | [[File:CLEARING-GAP.JPG]] | ||
== Ion Precipitators == | == Ion Precipitators == | ||
# [https://logbooks.jlab.org/entry/3471482 ion collectors and anode current] | # [https://logbooks.jlab.org/entry/3471482 ion collectors and anode current] | ||
# [https://logbooks.jlab.org/entry/3471521 The downstream ion collector was wired incorrectly] | # [https://logbooks.jlab.org/entry/3471521 The downstream ion collector was wired incorrectly] | ||
| + | # [https://logbooks.jlab.org/entry/3471688 comparing vacuum conditions 1 mA run 11 Jul 2016 with 28 Apr 2017] | ||
# This is a sketch of the internals of the downstream ion collector VICGT06 | # This is a sketch of the internals of the downstream ion collector VICGT06 | ||
# [[File:Sketch of ion colelcotr internals VICGT06.jpg]] | # [[File:Sketch of ion colelcotr internals VICGT06.jpg]] | ||
Latest revision as of 12:34, 2 May 2017
Attempted to run at 1 mA
- Ran for few seconds before a HV arc. QE dropped by a factor of 2.
- Ran again for 1.5 hours with ion-precipitators on (?) before a HV arc. QE dropped by another factor of 2.
List of Tasks (Down Monday – Wednesday)
- Re-activate photocathode with 3 mm active area
- Degas dump with NEGs at 2 Amps AC on for ion pumps to take vacuum load
- Laser ND Filters:
- Wheel filters are physically out of laser path (cannot be used).
- ND filter with In/Out box in GTS control room can still be used. Is has ND1 filter (a factor of 10).
- Shukui installed ND3 filter on spare servo motor 2. We should start using this ND filter. It is now on the Tool Screen.
- Instrument wire scanner
- Installed WiFi access point in GTS cave and enabled JMenu on PC using NX-Connects and Two-Factor Authentication. Then: ssh fell08, jmenu MainMenuGTS.
- Why is Dump/FC picoammeter reading is noisy? up to 20 nA.
- Hi-pot VIPGT06
- SCAM VL LINE SYNC frequency is not 60 Hz? Need 60 Hz Beam Sync Chassis. Will run with "FREE RUN" mode at 60 Hz.
- Put ND filter in front of ITVGT06 and mount camera on the floor.
Beam Gap Clearing
- An alternative to applying electric field (bias) is removing intrinsic electric field (beam)...
- Beam 'off' time of ~few microseconds w/ rep rate at least greater than ~100 Hz should do OK
- Additional 'do something' half-wave plate within tune mode generator + User mode...
- Spinning optical chopper ?
Ion Precipitators
- ion collectors and anode current
- The downstream ion collector was wired incorrectly
- comparing vacuum conditions 1 mA run 11 Jul 2016 with 28 Apr 2017
- This is a sketch of the internals of the downstream ion collector VICGT06
- These are Cornell's results
- Grames paper on anode bias: Media:Grames_PST07_final.pdf
- Pozdeyev PAC 2007 ion trapping: Media:Pozdeyev.PDF
- Cornell PRAB paper on ion clearing electrodes: Media:Cornell ion colelctors PhysRevAccelBeams.19.034201.pdf
- Gabriel's calculation (POISSON model) of the voltage needed in upstream ion collector (VICGT04, wire sticking out of the spool piece): Media:Ion collector VICGT04 wire stikcing out of spool piece.pdf
- CEBAF vacuum during 1 mA run
- GTS vacuum 1 mA run April 28 2017
- GTS 1 mA run also tripped 1.5 hour July 11 2016
