Daniel, Elenna, Vicky, Gabriele. After the confusing results of last nights ring heater changes (alog68777), we wonder if the peaks are swapped from what we thought, X lowest frequency, Y highest.
We increased ETMY ring heaters to 1.7W/segment to match ETMX. We are hoping the squash the peaks as in 1.0W/1.0W settings 68491.
I also remade Dan's 68715 plot with all plots after 2 hours of max power into IFO. See attached.
There has been a lot of fiddling around with ring heaters today (cue clown music). Here is a list of lessons learned, and a quick summary of where we ended up.
Lessons learned:
- The pointy peak is Y arm, the rounded peak is the X arm. They never switched places.
- We tried high ring heater- 1.7 W and 1.7 W and moved the peaks below the acoustic mode forest but tanked the PRG by 20%
- we think this is a "double whammy": increasing RH lowers the PRG. This drops the circulating power. Then there is less absorption in the arms
- There is a 10.2 kHz PI on ETMX that we are not yet set up to damp, but we can mitigate it
We have moved back to a similar configuration to where we started. EX is set to 1.4 W, EY is set to 1 W. We are happy here: the squeezing looks great, the bucket noise is very low, the frequency noise is not worse than usual.
Given the higher contrast defect measured at these settings, Dan and I have decided to step ETMX RH down to 1.3 W and see if that improves the CD. The measurement can be taken 3 hours from now.
Lots of changes last night, IFO was left with ring heaters at 1.3W/seg on ETMX and 1.0W/seg on ETMY. These are the same settings we had Friday 14th - Monday 17th.
Plots attached of the lock last night with various changing settings. Elenna's contrast defect measurements mentioned above are alog 68812
