janos.csizmazia@LIGO.ORG - posted 17:19, Tuesday 20 August 2024 - last comment - 17:39, Tuesday 20 August 2024(79615)
8-20 vent vacuum diary
Today's activities: - After the replacement of the PT-154 gauge (https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=79599), and after the small volume of the gauge was pumped overnight, now it has been valved together with the main volume - The small Pfeiffer turbo, along with the leak checker was taken off from the gauge's volume - Then, the HAM7-BSC3 small FCT section was valved together with HAM7 - FCV-1 opened - The 2 aux carts have been taken off from the HAM5/HAM6 annulus system - An aux cart was added to GV7 for safety reasons, to protect its annulus system during opening it up - The HAM6 turbo was valved out. The reason for valving it out so early is that the backing scroll pump had horrendous noise, so it needs rebuilding, and would have not been a good decision to let it run overnight. Especially, that the backing pressure was slowly growing. The hoses, cables, and the cart was also put away - RGA scans were collected at the corner, before opening up the large gate valves - GV5 and GV7. The results will be posted to the comment section
Corner RGA Scans
RGA Model: Pfeiffer Prisma Plus
EM Voltage: 1200V
Dwell Time: 500ms, 0-100 AMU
Valve States: GV5 & GV7 closed, RV1 closed, FC2 & FC3 closed (Relay Tube & FC Tube valved out of corner)
Pumping: 4x 2500 l/s Ion Pumps, 1x 500 l/s ion pump (HAM6), 3x 2000 l/s Turbo pumps
RGA Volume had been pumped with 80 l/s turbo & aux cart throughout duration of vent, but these were not valved in to RGA volume during scan collection, RGA filament on for ~1 week before scans collected
Corner Pressure at time of scans: 1.15E-7 Torr (PT120B)
Raw data files will be collected at T2400297
Last attachment is a comparison to the March pumpdown, which had GV5 and GV2 closed, 4x 2500 l/s IPs, 1x 500 l/s IP, 2x 2000 l/s TPs, March scan collected after ~12 days of pumping
August pumpdown started 8/6/24, and turbopumps were turned on on 8/7/24, corner has been pumping for 13 days, GV1 & 2 opened on 8/12/24