GTS meeting 5 02 17
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 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