J. Kissel

Took regular charge measurements yesterday. Results for ETMY are beginning to wash out what effects we thought we might have seen after the July 6th 2017 EQ -- I'd argue that it's now a toss up in terms of each quadrant whether the effective bias voltage showed a significant step, or just apparently so given the gap in the data for ~6 weeks. ETMY's worst quadrants (ETMY UL in Pitch) are now at -93 [V], which is about 25% of the applied effective bias voltage (380 [V]). However, though angular the effective bias voltage has changed from -11 [V] to -92 [V] (a change of (93-11)/380 = 21%), the relative actuation strength in longitudinal -- as measured by calibration lines, reported on the summary pages -- has only changed by 10%. 

ETMX remains at a reasonably low level of effective bias voltage, where the worst quadrants (ETMX LL and LR) are showing effective bias voltages of ~40 [V], but the mean (average of all eight measurements, 4 quadrants in P and Y) is 20 [V]. This is mildly inconsistent with what Sheila has measured recently -- -5.2 [V] -- via longitudinal drive (see LHO aLOG 38233) However, I look forward to seeing the results of the test mass discharge system, slated to be used next Tuesday (2017-08-29).

All effective bias voltages reported by the angular actuation strength have an uncertainty at the level of 1-2 [V]