J. Kissel

This is your weekly ETM charge measurement update! While charge continues to slowly accumulate on both test masses, I think we can begin to say that the rate of charge accumulation (as measured by effective bias voltage and L, P, and Y actuation strength) is slow enough on H1 SUS ETMY that we can get through the remainder of the run without flipping the ESD bias voltage sign, and retain low enough systematic error in the calibration model to stay within the desired 10%. However, one of the first things we should consider doing once the run is complete (after the calibration run is complete) is reducing the bias voltage by half to continue to slow the rate of charge. Oh, and H1 SUS ETMX continues to slow its accumulation rate thanks to our high duty cycle and turning of the bias when its not needed.

See attached images for depictions of the trends both in effective bias voltage and actuation strength in Pitch and Yaw (+ Longitundinal for H1 SUS ETMY).