sheila.dwyer@LIGO.ORG - posted 22:10, Tuesday 25 September 2018 - last comment - 22:32, Tuesday 25 September 2018(44164)
Powered up to 22W
Georgia, Craig, Stefan, Thomas, Danny, Stefan, Hang, Sheila
We powered up to 21 Watts input power, and were stable there for 10 minutes. We lost lock powering up to 24W input power, but that may have been due to a transient that saturated the test masses while we are increasing the power.
- We are using different soft offsets than what we had set at 2W input power, we probably just need to check for good offsets after powering up and set them that way.
- Our power recycling gain at 2 W input power is 50. We recalibrated the LSC_PR_GAIN channel based on the average of the two TR_X_NORM channels.
- After powering up to 10 W at 3:44 Sept 26 UTC , we sat for about 25 minutes and our TCS team reduced the CO2 powers to 200mW CO2X and no power on CO2Y. The AS power looked better and the OPO power became more stable with the reduced CO2, but we think that we overshot a little.
- We powered up to 22W and were stable there for a bit over 10 minutes.
- At each power increase step we saturated the suspensions. We tried turning of the violin mode damping, and tried engaging the low pass on the power normalization. We continued to saturated
- Based on the newly calibrated circulating power monitors there was 7kW in the X arm and 6 kW in the Y arm at 2W input power. The asymmetry in the two arm powers seems suspicious. but as we powered up the recycling gain dropped to 43, the Y arm power was reported as 77kW while the X arm power was reported as 60kW.
- We lost lock probably due to one of the saturations/transients as we tried to step the input power to 26W.
- We left both the SRC ASC loops off while powering up, and at 10W we checked the lock point of BS, which seemed fine at that power. The SRM error signal was still zero'd after powering up to 10W,, at 20W we saw a slow drift.
Things that we want to do:
- Engaging the CARM boost
- Running A2L which might help prevent the saturations as we increased the power.
- Phasing AS36 and AS72 and checking the lock point and sensing for BS and SRM after we power up.
- Engaging the OMC low pass while we are locked on RF
- Centering the IMC WFS.
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We've been struggling with ALS-X glitches again tonight, so on Keita's advice we looked at the X-end laser. Laser diode power monitor 1 seems to become twice as noisy, but it's very hard to tell with the slow monitor channels. The glitches went away again, but it could be worth it to investigate the X-end laser itself the next time we see these glitches.
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