Gerardo, Jordan, Travis, Janos Reacting to the issue in aLog https://alog.ligo-wa.caltech.edu/aLOG/index.php?callRep=80370, the HAM1 AIP was checked for controller and pump failures. After trying a couple of controllers, it was clear that the pump broke down. Shortly after the maintenance period, because of the high seismic activity, locking was impossible, so the vacuum team took the opportunity and swapped the pump (as normally it would have been impossible during the 4 hours of the maintenance period). The AIP was swapped with a noble diode pump - this was not exactly intentional, but turned out to be a happy accident, as it seemingly works much better than the Starcell or even the Galaxy pumps. However, as the noble diode pump has positive polarity, a positive polarity controller was needed: the only available piece is an Agilent IPC Mini (see it in the picture attached), which works well, but in the MEDM screen it appears to be faulty, due to its wiring differences. All in all, the HAM1/HAM2 twin-annulus system was pumped with the 2 AIPs and an Aux cart - Turbo pump bundle. The noble diode pump stabilized very nicely (at 5-7E-7 Torr, which is unusually low), so eventually the Aux cart Turbo pump bundle was switched off - at 6:55 pm PT. Since then, the 2 AIPs continue to decrease the annulus pressure, which is indeed very nice, so practically we are back to normal. In the meantime, Gerardo quickly modified an appropriate Varian controller to have positive polarity, so at the next opportunity the vacuum team will swap it with the Agilent controller, so the MEDM screen will also be normal. Note that the Aux cart - Turbo bundle remain there until this swap happens.
While the ion pump was replaced we managed to trip the cold cathode giving us the signal for the vacuum pressure internal to HAM1, PT100B, found the CC off last night, but since the IFO was collecting data decided to wait until we were out lock, I turned the CC back on this morning. See trend data attached.
Diode pumps are typically faster than triode pumps including Starcell cathode types. Nice work!
Removed the Agilent IPC Mini controller that was temporarily installed on Tuesday, and replaced it with a positive (+) MiniVac controller. Attached is a trend of current load for both controllers, HAM1 and HAM2.
Note for the vacuum team, we still have the aux cart connected to HAM2 annulus ion pump isolation valve.