Hannah Fair, Stefan Ballmer

Just a few days ago the interferometer tended to loose lock at full input power (23W) in ~10 to 40min. (Hence the run is at 17.3W.)

We went back to the following lock losses:

1) Jun 02 2015 01:49:44 UTC    = GPS 1117245000
2) Jun 02 2015 03:53:19 UTC    = GPS 1117252415
3) Jun 02 2015 08:13:04 UTC    = GPS 1117268000
4) Jun 02 2015 11:33:54 UTC    = GPS 1117280050

All of them showed as immediate cause of lockloss a run-away of the MICH_Y ASC loop on a time scale of about 0.2sec. (0Plots 1-4).
However, lock losses 3) and 4) also showed a significant control signal drift in PRC2, SRC1, SRC2 (both Yaw and Pit) over about one minute time scale before the lock-loss.

We therefore suggest lowering the MICH_Y ASC gain slightly next time we try 23W, and then investigate the ASC signals, most likely for the SRC.