I measured the DARM sensing plant again today. Seems that we are prospring detuned again. Dan Brown did some last minute tuning, but I don't think he logged all of his changes. This alog is an attempt to recover the TCS situation.
With the loss of TVo and Dan Brown, we are hurting for thermal compensators at a time where the importance of thermal compensation tuning is at an all-time high, since we did not see a range improvement from increasing the power from 30 to 35 W.
Fortunately Danny VH will be returning after the LVC, but in the meantime we will do our best to tune TCS.
As best as I can tell, here is the current TCS situation at the time of this DARM measurement (~2 hours into a lock):
H1:TCS-ITMX_RH_SETUPPERPOWER 0.4 # W, ITMX ringheater
H1:TCS-ITMX_RH_SETLOWERPOWER 0.4 # W
H1:TCS-ITMY_RH_SETUPPERPOWER 1.3 # W, ITMY ringheater
H1:TCS-ITMY_RH_SETLOWERPOWER 1.3 # W
H1:TCS-ETMX_RH_SETUPPERPOWER 0.2 # W, ETMX ringheater
H1:TCS-ETMX_RH_SETLOWERPOWER 0.2 # W
H1:TCS-ETMY_RH_SETUPPERPOWER 0.2 # W, ETMY ringheater
H1:TCS-ETMY_RH_SETLOWERPOWER 0.2 # W
H1:AWC-SR3_HEATER_POWER_SET 5 # W, SR3 disk heater
H1:TCS-ITMX_CO2_LSRPWR_MTR_OUTPUT 0.6696 # W, ITMX CO2 power
H1:GRD-TCS_CO2X_MASKS_REQUEST CENTRAL
H1:TCS-ITMY_CO2_LSRPWR_MTR_OUTPUT 0.0778 # W, ITMY CO2 power
H1:GRD-TCS_CO2Y_MASKS_REQUEST CENTRAL
H1:TCS-ITMX_HWS_PROBE_SPHERICAL_POWER -0.000772 # diopters
H1:TCS-ITMY_HWS_PROBE_SPHERICAL_POWER 0.000193 # diopters
H1:LSC-POPAIR_B_RF18_I_NORM_MON 47.3192 # cts
H1:LSC-POPAIR_B_RF90_I_NORM_MON 15.1798 # cts
H1:PSL-POWER_SCALE_OFFSET 35.29 # W input power
H1:LSC-PR_GAIN_OUT16 45.0906
X Arm Power 175 # kW
Y Arm Power 192 # kW
It is hard to resolve the exact level of detuning with the current injections. The PCAL has limited actuation range, and we want enough power at high frequency to resolve the DARM pole, but also need to inject hard at low frequency to rise above the noise.
With prospring detuning we have to be careful not to inject too much at the spring resonance, which is difficult as it's exactly what we're trying to measure.
Our best bet is probably some bandlimited BB sweep from high to low frequency with appropriate notching at bounce and roll modes.