kyle.ryan@LIGO.ORG - posted 17:43, Friday 22 December 2017 - last comment - 09:56, Saturday 23 December 2017(39898)
Vacuum status
BSC1's annulus ion pump current looked good until it didn't. Now that the day is ending it looks like the AIP current has flattened (see attached graph). If so, we may have to deal with this on Tuesday. I sprayed helium around the outer O-ring of BSC3's recently installed door and didn't detect any smoking gun. The large leak on the pump plumbing (10 ft away) made interpretation harder than it would have been otherwise. I eventually fixed the 10-4 Torr range leak on the flex line and now the pump cart pressure and ion pump current are typical (see attached graph). Pump carts are pumping HAM1, HAM2, HAM3, BSC1 and BSC3. HAM5 and HAM6 annulus volumes can't be pumped unless we install rubber stoppers and the HAM6 door flanges. To do this, the "tacked on" South door of HAM6 will need to either be bolted or removed to allow installation of these. Mark D., Tyler G. and Bubba G. also installed the 3rd NEG pump atop the OMC in addition to installing doors and HAM2 and torqueing down HAM3's.
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I forgot to mention that I have isolated the purge-air supply from the, now, "buttoned up" Vertex+YBM+XBM volume (protects from loss of pressure regulation) and that the measured dew point today was -37C. Now that an hour has elapsed, I've attached an updated graph of BSC1 and BSC3 AIP currents (maybe hope for BSC1?) Leaving site now..... Have a MERRY CHRIST MASS and a HAPPY NEW YEAR!
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BSC 2 AIP was off before we vented. Investigation needs to be revisited.