After closing up BSC9 yesterday we started pumpdown of the EX volume this morning using the two mobile ISP1000 scroll pumps.
There was minimal overpressure in the system, so I could not get a good dewpoint measurement of the blow down air.
It took ~6 hours to rough the system down from atmosphere to ~500 mtorr, where we start the turbopump.
The cooling water was adjusted on the turbopump stand so that the pump and controller pressures were <= 40C. Once the turbo was at full speed and the inlet pressure ~5e-5 Torr, I switched the backing pump to the dedicated ISP250 on the turbo stand.
Setpoints were adjusted to 5E-2 Torr on Channel 1 (Foreline) and 5E-5 Torr on Channel 2 (Turbo inlet).
We will need to leak check the TMDS port gate valve since it was removed to verify the gate o-ring was in place.
Also, the EX cleanroom was powered off at ~3:10 pm local time.
Pumpdown update for X-End volume.
At this point only the turbo pump continues to pumpdown. See attached plot for progress.
Today we leak checked the TMDS port gate valve flanges (2.75" CF). We removed the gate valve during the vent to inspcet the o-ring as it looked like it may have fallen out, but after inspecting once the valve was removed, everything looked ok.
The helium leak detector was set up to back the main turbopump. There was no He signal detected above the leak detector background of 1.5E-10 Torr-l/s.
(Jordan, Travis, Gerardo)
BSC5 annulus ion pump update.
We isolated the aux-cart from the annulus ion pump on Monday by closing its isolation valve. The aux-cart was powered off on Tuesday after we noted that the ion pump was able to keep the vacuum pressure in the annulus system, then on Wednesday we removed all other equipment from the annulus system. BSC5 and its annulus system are back to nominal. Attached is a trend for the past 7 days of the pump behaviour.
