LEM at 1830 raised North Linac C1O0's and a few others up that created the heat load. Ops turned the C100's back to where they are running since Saturday and not doing any more gradient changes until Monday. We will monitor next weeks changes and suspect we will be trying to get the last of the C100 running and at higher gradients.
Was monitoring this zone since turn on last week and didn't lower to 10Mv/m before LEM today raised it to 11Mv/m and heating was taking the zone down. Good work C. Humphrey and thanks. Set to 10Mv/m in ODVH or drop gradient lower if needed.
The OPS DRVHs for the following cavities have been updated:
RF Status: Good
Tuner Status: Good
Comment: DRVH=10.000 Causing heat load at 11Mv/m. Been running at 10Mv/m until LEM raised to 11.
Previous OPS DRVH: 11
THOMAS JEFFERSON NATIONAL ACCELERATOR FACILITY
ACCELERATOR OPERATIONS CREW CHIEF SIGN IN FORM
Date : 11-02-19
Time : 23:05:53
Day : Saturday
Shift : Owl
Crew Chief : Frierson
Program Deputy: Michaud
Team : X
Arm : RADCON
Designated SSO: Surles-Law
Operators : Surles-Law
This stamp certifies that the above Crew Chief has read/reviewed/received the following:
Cavity three on 1L08 seems to have a heat issue. After all eight cavities had been turned on I proceeded to walk up cavity three to its ODVH; however, GSET increments of 0.100 made relatively drastic changes in the liquid level, which continued to rise resulting in a trip of the whole module.
1L20 cavities 1 and 2 brought back into RF after LEM left them off. They were still marked bad and being
monitored after repairs during commissioning of new cryo-module. Marked as good since they are tuned and look
good since Friday.
1L09-5 Was being monitored for CWWT at 8Mv/m and IR voltage seems stable at ~1.6v. This one was also marked
good in cavity history so it stays on to be monitored.
Checked up on some repairs Friday and they all stayed up after LEM was performed at 1830. Looking good and hope the best for the rest !!!
At 1900, the Cryo Coordinator reported low NL heater margin, which was - 10 watts per cryomodule.
I remotely logged in to see recent increase in RF power and increase in NL helium vapor pressure to 0.0397 atm.
To reduce NL helium vapor pressure, I increased SCN cold compressor flow from 195 g/s to 199 g/s, which would eventually restore heater margin.