I started to change the ESD bias and adjust the gain to compensate it.  The goal of this is to see if there is any change to the DARM noise, bicoherence, or coherence with EX power monitors for the full bias, and we were also planning to revisit the excess noise seen at -125V ESD bias back in Feb. 

We lost lock due to a site power glitch, so I'm just recording here the settings to be used to change the ESD bias and keep the DARM OLG and calibration the same. The second set of three references (positive biases) are settings found today, while the negative biases are settings found in Jan (66751), apparently the DARM loop has changed in the meantime. 

To do the test we intended today (get 20 minutes of quiet time at full positive bias), we would do:

• in a guardian terminal (type for example guardian -i ISC_LOCK)

ezca['SUS-ETMX_L3_DRIVEALIGN_L2L_TRAMP'] = 60
ezca['SUS-ETMX_L3_LOCK_BIAS_TRAMP'] = 60

• wait a second

ezca['SUS-ETMX_L3_DRIVEALIGN_L2L_GAIN'] = 47.22
ezca['SUS-ETMX_L3_LOCK_BIAS_GAIN'] = 2.85

• this will ramp the ESD bias up for 60 seconds and compensate the DARM loop.   We'd wait here for 20 minutes to get some time.  Then we'd restore to the nomial configuration by typing:

ezca['SUS-ETMX_L3_DRIVEALIGN_L2L_GAIN'] = 184.65
ezca['SUS-ETMX_L3_LOCK_BIAS_GAIN'] = 1

this will ramp the bias back to it's normal 125V value over 60seconds.  Then we can clear the SDF for the TRAMP:

ezca['SUS-ETMX_L3_DRIVEALIGN_L2L_TRAMP'] = 10
then we should be able to go back to observe.