Jenne, Sheila, Evan, Kiwamu
Today we aimed to have a long stable lock at 30 Watts. We did have one lock of more than half an hour at 30 Watts, which we lost due to commisioner error.
- We measured the coupling of test mass pitch to arm power fluctuations. More information will be coming later.
- We noticed that we can loose lock because of the CSOFT instability driven by power fluctuations when we power up too quickly for our soft loops to keep up. We rewrote the INCREASE POWER state to pause and wait for soft loops at 10 Watts intervals.
- In 3 out of our last 4 locking attempts, we have lost lock in DARM offset. The one time we made it Jenne did the steps in the guardian by hand. There don't seem to be any changes in the code for this state....
- We had a few locklosses engaging the ISS 2nd loop. The thresholds needed to be adjusted, now it is working.
- We did some A2L tuning today.
- We had a couple of sudden locklosses, where our recycling gain was slowly decaying, and it looks like the PR2 (REFL WFS) loop and SRC2 (AS_C to SR2 and SRM) loops ran away in the last fractions of a second. This seems like the lockloss we had because of the sign flip in the REFL WFS, because we increased the bandwidth of the PR2 loop it is now a fast lockloss. We measured the open loop gain of PRC2 both at 30 Watts (where the recycling gain is decaying) and at 2 Watts, the optical gain is lower at the 30 Watts measurement which was taken right before one of these locklosses.
- We decided based on this to try moving soft loop offsets, but we want to picomotor the TMSY QPDs before moving the offsets... we are leaving this for tomorow... We turned off the CHARD blends so that we can move picomotors, and are leaving them off for now, but should turn them back on when we are done with picomotors.
Also, the ISS 1st loop is oscillating pretty much every time we loose lock and needs to be fixed by hand. we are leaving IFO undisturbed at 23 Watts 7:50 UTC
[Jenne, Abdul, Lindsey (high school visitors)]
We used the picomotors on TMS Y to center the beams on the transmon QPDs. TRY_B looks much better now - no more factor of 40 between the amount of light on each segment. TRY_A still has an odd "butterfly" pattern, where the diagonal elements match, but the 2 diagonals are different from eachother by a factor of 2.
We reset the SOFT offsets with this new pointing, and successfully closed the SOFT loops. We may consider doing the same for TRX, but it's not nearly as necessary there. The Xarm picoing has been done, SOFT offsets reset with the new pointing to the diodes, and SOFT loops closed.
Now we're ready to move around a bit to see if we can minimize dP/dTheta.
I have put the CHARD blending back in, since the picomotor moving is finished.