Difference between revisions of "GTS meeting 5 02 17"

Latest revision as of 12:34, 2 May 2017

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.

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:
1. Wheel filters are physically out of laser path (cannot be used).
2. ND filter with In/Out box in GTS control room can still be used. Is has ND1 filter (a factor of 10).
3. 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.

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

@@ 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.
 # Instrument wire scanner
-# Install WiFi access point and enable JMenu on PC in GTS cave
+# 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
@@ Line 19: / Line 19: @@
-== Beta Calculations ==
+== Beam Gap Clearing ==
-:: [[media:Sajini_April2017_Beta_calculations.pdf]]
+*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 ==
 # [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/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
 # [[File:Sketch of ion colelcotr internals VICGT06.jpg]]