Reports until 00:21, Tuesday 14 June 2016
H1 SUS (ISC)
nutsinee.kijbunchoo@LIGO.ORG - posted 00:21, Tuesday 14 June 2016 (27716)
Violin mode damping work

Overall violin modes situation improved by a little more than an order of magnitude. Currently the modes with highest magnitudes are 501.092 (IX Mode3, lost lock before I could find the damp setting), 501.606 (IY, damp setting found but didn't have much time to damp), and 507.194 (EX, no damp setting yet).

 

Modes with newly discovered damp settings:

505.71 & 505.707: EX Mode3: FM1, FM2, FM4, FM5 +20 gain seems to work for both lines. After I noticed the filter stopped damping I turned off Mode 3 gain and turned on Mode2 gain based on Sheila's configuration here. This configuration will damp the modes even further. We lost lock before I could confirm that it won't blow either .71 or .707 up.

505.587: EX Mode1: FM1, FM4 +50 gain

507.159: EX Mode6:FM1, FM4 +gain (forgot to write down how much gain exactly. Probably no more than 100)

507.391: EX Mode8: FM1, FM4 +50 gain

500.05: IX Mode1: FM1, FM4, +50 gain. +100 gain will damp the mode but later will blow it up. +50 gain seems to have worked pretty well.

502.744: IX Mode8: FM1, FM3, FM4, +10 gain (BP, +60deg, 100dB)

502.621: IX Mode7:FM1, FM4 +50 gain (BP, 240dB)

501.606: IY Mode1: FM1, FM2, FM4, +150 gain

 

All these information has been updated to the new violin mode table but haven't been implemented into the guardian.

 

Tonight I also confirmed all the filters that VIOLIN_MODE_DAMPING Guardian turns on (I didn't confirm the exact gain, but I did confirm the filter configuration and gain signs). They should be safe to turn on.

Images attached to this report