Reports until 13:23, Monday 19 September 2016
H1 SUS (CAL, DetChar, ISC)
jeffrey.kissel@LIGO.ORG - posted 13:23, Monday 19 September 2016 (29799)
Charge Measurement Update; On Schedule to Begin Regular Flipping At Start of ER10
J. Kissel 

I've measured this week's charge assessment early, just to get it out of Tuesday's way while opportunity struck during ISS improvements this morning. 

All is well: charge continues towards zero, and it looks like in a few weeks -- at the start of ER10 -- we can try regular ESD bias flipping again. 

Impressively, but perhaps inconsequentially, the rate of charge on ETMX has increased substantially over the past few bias flips. However, this may also be a function of how much time we've spent over the past few months commissioning with the DARM drive still on ETMX. The fluctuation of actuation strength of ETMX is not important to calibration, and lock acquisition is not-so-sensitive to it, but this fast rate may confuse our assessment of the charge from week-to-week while it hovers around zero. Perhaps we should consider -- during ER10 at least, if/when we begin regular flipping -- measuring charge twice a week, just to get more that one data point per flip. 
Images attached to this report