daniel.vander-hyde@LIGO.ORG - posted 17:47, Sunday 17 February 2019 - last comment - 16:15, Monday 18 February 2019(46975)
morning/afternoon locking
- First lock:
- made it up to nominal low noise but lost lock due to what appears to be CSOFT pitch (please see first attached figure).
- right before the lockloss it looks like the ETMX L2 stage was periodically saturating every 5 seconds or so
- Second lock:
- Decided to settle at LOWNOISE_ESD_ETMX to see if this might be because of our DARM actuator changes made yesterday
- Lost lock at LOWNOISE_ESD_ETMX. ETMX L2 stage was saturating again before the lockloss.
- Third lock:
- Commented out the final bit of code in LOWNOISE_ESD_ETMX that transitions the L2 stage actuator from ETMY to ETMX (alog 46969 and 46973). So the DARM actuator will be ETMX L1, ETMY L2, ETMX L3.
- Stable at LOWNOISE_ESD_ETMX for about 6 minutes.
- Transitioned to LOWNOISE_LENGTH_CONTROL. ETMX L2 started to saturate from CSOFT pitch ringing up so I reduced the CSOFT pitch gain from 30 to 20. (maybe the increase in gain from 15 to 30 at LOWNOISE_ASC might be too aggressive?)
- Changed DARM actuator to ETMX L1, ETMX L2, ETMX L3 by hand.
- After, I was able to make it to nominal low noise just fine.
- Restored actuator changes in guardian.
- Low frequency noise (10-50 Hz) doesn't look as good as yesterday (please see second attached figure).
- Thought this might be increased ASC noise from me reducing the CSOFT pitch gain but after looking at the CSOFT filter at NLN it looks like it's the opposite (please see third figure) so I'm leaving the CSOFT pitch gain at 20.
Images attached to this report
Comments related to this report
This lock lasted more than 20 hours.
A bruco scan is available here. There is a lot of coherence with the ETMX L1 FASTIMON channels, which are just seeing DARM, which I've now added to the excluded channels list. Other than that we have a few things of interest:
- ASC noise below 30 Hz ITMY_L2_NOISEMON_LL
- SRCL at 27.7 Hz
- Line coherent with magnetometers in the remote racks at EX around 73.5 Hz
- HAM5/6 septum accelerometers at 90 Hz. This had been peaking above DARM, but the peak seems to have been reduced sometime between Feb 3rd and now.
- Laser noise at high frequencies
