gabriele.vajente@LIGO.ORG - posted 08:51, Friday 12 October 2018 - last comment - 15:05, Friday 12 October 2018(44513)
Morning lock report
6:05am started initial alignment:
Aligned X arm by hand to get power > 1, then engaged green WFS loops. After alignment converged, turned loops off by setting ASC gain to zero for X green
PRM and BS were off by large amounts
After initial alignment was done and offloaded, tried LOCKING_ARMS_GREEN: both arms were misaligned and not lockable on green. Had to adjust them by hand
Manually engaged MICH and SRCL feed forward, manually transitioned to CLOSE_BEAM_DIVERTERS
Started adjusting soft loop and POP_A offsets
Lock loss at 7:40 LT: unknown causes
In DRMI_LOCKED_CHECK_ASC, OMs were saturating, lost lock once
Once at LOWNOISE_ESD_ETMX (copying most of the LOWNOISE_LENGHT_CONTROL state, except for the part related to ITMX/Y L2 only drive, but that should be ok too)
switched on MICH and SRCL feedforward
Changed SRCL gain to -11, PRCL gain to 16 to improve gain peaking
Enagaged MICH FM1 and SRCL FM3 (boosts)
manually transitioned to CLOSE_BEAM_DIVERTERS
8:25am, handed off IFO to Robert for PEM injections
Comments related to this report
gabriele.vajente@LIGO.ORG - 09:20, Friday 12 October 2018 (44515)
DHARD_P gain this last lock was just a bit too high. I lowered it from -40 to -35. This gain has been bouncing up and down the last few days, since we started going to 20W. We need to measure this loop when we have a chance, and also tune the radiation pressure compensation for 20W (it's currently tuned for 10W, and we don't have power-dependent code in there).
I did not put this gain change into the guardian, since -40 worked earlier today and all yesterday.
haocun.yu@LIGO.ORG - 15:05, Friday 12 October 2018 (44527)
Jenne, Sheila (Sheila, logged in as Haocun by mistake)
We think the problem with DHARD that Jenne is talking about above is due to a bounce mode being rung up a bit. Now that we have dampers they ring down on their own within a couple of minutes so we haven't tried to do anything about this, but if needed we could monitor the amplitude and wait for it to ring down before increasing the DHARD gain.
DHARD_P gain this last lock was just a bit too high. I lowered it from -40 to -35. This gain has been bouncing up and down the last few days, since we started going to 20W. We need to measure this loop when we have a chance, and also tune the radiation pressure compensation for 20W (it's currently tuned for 10W, and we don't have power-dependent code in there).
I did not put this gain change into the guardian, since -40 worked earlier today and all yesterday.
Jenne, Sheila (Sheila, logged in as Haocun by mistake)
We think the problem with DHARD that Jenne is talking about above is due to a bounce mode being rung up a bit. Now that we have dampers they ring down on their own within a couple of minutes so we haven't tried to do anything about this, but if needed we could monitor the amplitude and wait for it to ring down before increasing the DHARD gain.