Reports until 16:41, Thursday 01 June 2017
H1 FMP
jeffrey.kissel@LIGO.ORG - posted 16:41, Thursday 01 June 2017 (36598)
End-Station Temperature Update: Removal of B Sensor Helped a Little, but looking for ~0.05 [deg C] Stability
J. Kissel

As we're finding trouble with the new ALSX laser either producing multiple modes or mode hoping, I'm find more reasons to pay attention to the VEA temperature, and more reasons to wish for the stability of the older HVAC system. Bubba's recent modification to the error signal (i.e. removing an errant sensor from the average; see LHO aLOGs 36527 and LHO aLOG 36536) did change the sign of the diurnal oscillations, but they're they're only slightly reduced in amplitude as they were, at ~0.2 [deg C] or 0.5 [deg F]. Apparently, the former system kept the VEAs stable to within 0.05-0.1 [deg C] (0.1-0.2 [deg F]) -- notably much better than the canonical iLIGO requirement of 1 [deg C]. 

Attached are 10 day trends of the past for each end station, before and after the upgrade. The after upgrade trend takes us up to the present.

For the record, I think at this point we should stick with whatever set-point temperature we have since we've been able to regain IFO alignment and sensitivity, adjust references to this new point, and we're now tuning the ALS laser performance to this temperature. Let's focus on improving (decreasing) the amplitude of diurnal oscillations.

P.S. Remember I continue to show the PCAL sensors because they're the most calibrated and the receiver module's temperature was most similar to what the former FMCS sensors reported. All other temperature sensors in the VEA *besides* the current FMCS sensors show this oscillation, so it's not just a function of the location of this particular sensor.
Images attached to this report