camilla.compton@LIGO.ORG - posted 12:05, Thursday 30 May 2024 (78144)
Lockloss from Swapping from ITMX to ETMX ESD DARM control
Camilla, Sheila, Robert
We successfully swapped from EX to IX ESD DARM control for Robert's bias sweep by manualling SUS_CHARGE to SWAP_TO_ITMX. On the swap back we again manualled SUS_CHARGE to SWAP_BACK_ETMX, this caused a lockloss as we forgot to return the ETMX bias to it's normal value so the BIAS MASTER_OUT_DCMON was around -487,000 rather than the nominal +170,000. Sorry.
Unrelated to today's lockloss but should stop lockloss caused by in-lock charge measurements: commit 27861
This SWAP_BACK_ETMX state has been causing locklosses on Tuesday mornings since we've swapped to new DARM. Today we found this was due to out of date L3_DRIVEALIGN_L2L filter settings (FM4,5 rather than FM7) hard-coded in RAN_ESD_EXC.py. We edited this and expect this will stop future locklosses from in-lock charge measurements. Sheila also found a ramping inconsistency in SUS_CHARGE SWAP_TO_ITMX that we were surviving, edited that too.
Changed in-lock excitation frequencies to suggested new ones that avoid 14Hz roll mode we never used from 76492: ETMs 12Hz, ITMX 13Hz, ITMY 15Hz. Now we've got recent data with all test masses. Tagging SUS.