Reports until 18:36, Wednesday 15 March 2023
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gabriele.vajente@LIGO.ORG - posted 18:36, Wednesday 15 March 2023 - last comment - 15:43, Friday 17 March 2023(68012)
Summary of CHARD_Y work

Unfortunately it's not clear yet if the new configuration is stable on the long term.

In particular, I'm not sure if the 3.3 Hz damping on the reaction chain is doing anything useful at all. I convinced myself that the ETMs have the same signs that the ITMs. While unlocked, I could ring the mode up with the wrong sign, and damp it (slowly) with gains of P = 3, R = -10
In lock, the 3.3 Hz oscillation in all ASC signals and in ETMX M0 L is still rising with time.

To engage the new controller:

None of the above is automated, but the R0 dampers are accepted in SDF

Comments related to this report
thomas.shaffer@LIGO.ORG - 09:35, Thursday 16 March 2023 (68029)
Link

For reference attached is a screenshot of what we accepeted yesterday. We will continue to try these for a bit today and back them out if we don't see improvement.

Images attached to this comment
ryan.short@LIGO.ORG - 09:46, Thursday 16 March 2023 (68030)
Link

SDF screenshots for updated gains for ETMX/Y R0 damping filters.

Images attached to this comment
thomas.shaffer@LIGO.ORG - 15:43, Friday 17 March 2023 (68046)
Link

We tried this for a bit today with the same results. Brief time line:

  • 13:04PT - we verified the R0 settings and then changed the CHARD Y and CHARD Y RPC as Gabriele instructed above
  • 13:19 - briefly reverted settings due to excessive saturations
  • 13:22 - brought back to Gabriele's setting above
  • 13:41 - changed the CHARD Y gain to 80 from 100 to help with the saturations
  • 15:15 - Lockloss. The familiar CHARD Y ringup