jeffrey.kissel@LIGO.ORG - posted 16:07, Thursday 10 January 2019 - last comment - 10:34, Friday 11 January 2019(46349)
H1CALCS TDCF Reference Model Epics Records Updated to Fix Sign Issues
E. Goetz, J. Kissel Continuing progress after yesterday's win in producing time-dependent correction factors LHO aLOG 46328, today I tackled item (1): Evan, Lilli, and Shivaraj have put in a lot of good work exposing and fixing residual problems with the python suite of code now used to create the DARM model ("pyDARM") when it comes to getting signs right; see G1900019. As such we now believe we have it all right. Thus, I've now - updated the pyDARM suite, /ligo/svncommon/CalSVN/aligocalibration/trunk/Common/pyDARM/src/ actuation.py sensing.py computeDARM.py - regenerated and installed the epics records that report the DARM loop model at the calibration line frequencies for use in calculation the time dependent correction factors, using zotws10:/ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O3/H1/Scripts/CALCS_FE$ python3.5 createEPICS_for_20181205.py -w The only changes are in signs -- no magnitude change (see item (3) below). The magnitudes remain the same as they were for ER13. The record of these new results can be found in /ligo/svncommon/CalSVN/aligocalibration/trunk/Runs/O3/H1/Results/CALCS_FE epicsrecords_model-H1_20181205_created-20190110.txt for use elsewhere. Still to do: (2) The gating system (which smoothes out the TDCF for application to DELTAL_EXTERNAL) and override system (which allows us to bypass non-functional parts) don't yet have all settings turned ON in such a way that the relative actuator strength changes -- a.k.a. kappa_UIM, kappa_PUM, and kappa_TST -- are spitting out live values. In this brief moment in time where the optical plant parameters were working, all of the actuator kappas were bypassed and spitting out +1.0. (3) As mentioned above we're still using a pre-ER13 measurement to determine the DARM loop reference model, which in turn determines the EPICs records, which determine the calculated TDCFs. The actuator measurements were quick and dirty. The IFO was still at 20 watts. Thus -- when I see that the corrective gains, the kappas for both actuator and optical plant, have magnitudes at the 10-30% level, I'm not yet sad. Now that we're electing to stick at 30W input for a while, while we hunt for noise, we should re-take -- or in some cases take for the first time -- quality measurements that will get the system to levels needed for ER14 / O3.
A sneak peak at the interferometer power up from 2 to 30 W and the transition from some ETMY DARM control to full ETMX. Comments: - The signs of all TDCFs are right! - The calibration lines are loud enough that one starts to get sensible signals by the time we're in DC readout. - There're some kicks to the system when we pass through switching to low noise coil drivers, when we transition EY to EX, and ... something when we land in nominal low noise. To be determined, and hopefully fixed. - The change of the kappa_UIM and kappa_PUM from close to 1.0 to 1.4ish happens exactly when UIM and PUM control transition from EX to EY. Probably right. I can easily believe that the UIM and PUM between stages are 40% different (or there's just some gain that shouldn't be there in the replica actuator path... CRAIG...). - The relative optical gain (kappa_C) passes through 1.0 right around when we're at 20 W -- which is what the reference model is tuned for, and then gets stable at 90% once we're at 30W. Also makes sense! - Cavity pole frequency remains pretty stable throughout the power up, only a ~10 Hz drop. Not bad! Twas on a downward trend though. - Lots of things to work out when it comes to divide-by-zero problems in the optical spring parameters... If you like these ndscope templates, they live here: /ligo/home/jeffrey.kissel/Templates/NDScope/ CAL_tdcfs_actuatorplant.yml CAL_tdcfs_opticalplant.yml