Reports until 00:54, Saturday 26 March 2016
H1 ISC
sheila.dwyer@LIGO.ORG - posted 00:54, Saturday 26 March 2016 - last comment - 14:53, Wednesday 30 March 2016(26267)
ASC phasing script, not stable above 10 Watts yet

We did a little bit of ASC work today.  

First, while Kiwamu was running a TCS test I started a script to automate phasing of the WFS.  It uses the lockin, first runs a servo to set the phase of the lockin demod, then servos to minimize some signal.  We have it set up right now to phase the refl WFS to minimize the PR2 pit signal in Q for both REFL 9 and 45, and to minimize the SRM pit signal in AS 36 Q.  There is some code for exciting DHARD, but we need to test amplitudes, phases and gains for this.  The current version of the script does its job although it is painfully slow, and is checked into the svn under asc/h1/scripts  THe resulting phases are in the attached screenshot. 

We saw that the instability in CHARD pit was becasue somehow the LP9 got turned on again, this is now off and CHARD seems fine.  

We tried powering up, were fine at 10 Watts.  We had an instability in PRC1 and PRC2 yaw at 13 Watts.  I reduced the Q on the complex zeros at 1.1 Hz for PRC2Y, which gives us slightly better phase and gain near the point where we seem to be unstable. Attached is a screenshot of the OLG measured with white noise at both 2 Watts and 10Watts, we might need to do a swept sign to get a good measurement around 1 Hz. 

After about 10 minutes at 12 Watts, we had the usual fluctuations in the recycling gain.  So the high bandwidth PRC2 loops haven't totally solved the problem. 

For the record, these are angle settings that give approximately good CO2 powers tonight, and the powers to aim for from Kiwamu's note:

  X power (W) X angle Y Y angle
unlocked 0.5 76 0.23 82
10W   78   79
20W 0.3   0.1  

We have twice had the rotation stage for CO2 Y go to an angle that was wrong by a lot (sending a few watts to the test mass for a few seconds).

I'm leaving the IFO locked at 10Watts. 

Images attached to this report
Comments related to this report
john.worden@LIGO.ORG - 09:14, Saturday 26 March 2016 (26268)

Sheila,

Do you know how much power was transmitted at CO2 Y to any precision? Can you say what the upper limit was?

 

thanks

sheila.dwyer@LIGO.ORG - 16:14, Monday 28 March 2016 (26294)

The first time  H1:TCS-ITMY_CO2_LSRPWR_MTR_OUTPUT read back 3.2 Watts for about 20 seconds.  

THe second time H1:TCS-ITMY_CO2_LSRPWR_MTR_OUTPUT  read 3 Watts for about 10 seconds. 

sheila.dwyer@LIGO.ORG - 16:34, Monday 28 March 2016 (26295)

This morning I looked at some of the data from friday night when we had our usual CSOFT instability.  (16-03-26 7:52:56 UTC)

First, I used the moment of interia here, and the calibration of the arm circulating power from the transmon QPDs here, to estimate i it is reasonable that radiation pressure due to the fluctuations in arm circulating power (on the order of 2.5% fluctuations on 35 kWatts of circulating power) could cause the angular motion that we see (0.1-0.4 urad pp on the test masses), and it is not, the miscentering that would be required is far too large.  

sheila.dwyer@LIGO.ORG - 14:53, Wednesday 30 March 2016 (26343)

I never attached the sreenshot of the PRC2 Y OLG to the original alog.  Here it is. 

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