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Reports until 15:39, Thursday 22 May 2014
H1 SUS
keita.kawabe@LIGO.ORG - posted 15:39, Thursday 22 May 2014 (12026)
ESDX investigation

I manually measured the equivalent bias voltage of ESD caused by the charging for ETMX by looking at the oplev.

I changed the bias voltage (-377V, 0, 377V) and measured the transfer coefficients from the drive to the quadrant to the oplev at 3Hz.

In the case of UL and LL, I also put some offset in the quadrant output so I have a larger dc voltage difference between the bias and the quadrant.

As you can see, though it's not a perfect line as you can see in UL and LL, it looks very reasonable in that the absolute value of the slope of four quadrants are quite similar, plus PIT/YAW makes perfect sense.

The effective bias voltage obtained from PIT data and YAW data are different because it is dependent on where the charge is.

For each quadrant I fit the three data points that correspond to no offset in the quadrant itself and obtained these:

  UL LL UR LR
P charge effective bias [V] -161 78 -176 43
P slope [urad/V^2] 7.6e-8 -7.0e-8 7.8e-8 -6.0e-8
Y charge effective bias [V] -201 -60 -233 -88
Y slope [urad/V^2] 7.3e-8 7.3e-8 -6.5e-8 -6.9e-8
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