camilla.compton@LIGO.ORG - posted 14:49, Thursday 21 April 2022 - last comment - 16:55, Thursday 21 April 2022(62725)
ITM ring heaters turned on
After looking at images in alog 62718 during the LHO commissioning meeting we are going to try having the ITM ring heaters on with different amounts. I've set ITMY 0.5W/segment and ITMX to 1.0W/segment.
Reasoning: from the images 0.68W/seg made ITMY with 50W IFO beam look a similar curvature to when cold after ~1h30m of RH so going a bit less than 0.68W. Comparing the ranges of the top two no RH images we see that ITMX absorbs approximately double ITMY.
These are not set to turn off by themselves. If we have trouble locking later on this afternoon we may need to start ramping CO2 central heating before we power up.
For now I turned the ITM RH back off as it seems to make the corner worse RF18 signal quickly worse. Left plots are lock earlier. Right plots last lock are RH's on (ITMX 1.0, ITMY 0.5W/seg).
We were locked at 2W when I tried this test earlier then lost lock. We will try these values again once we have powered up.
If we are locked at 50W later, a lovely commissioners might turn these back on as a 4 hour ring heater test so that we'll start the morning with a cold IFO. ITMY 0.5W/segment and ITMX to 1.0W/segment. They will turn back to 0W after 4 hours.
tmux new-sessionpython3 /opt/rtcds/userapps/release/tcs/common/scripts/power_adj_scripts/ring_heater_schedule.py ITMY -s "now" -d 4 -p 0.5[CTRL] + [B] and then [C]python3 /opt/rtcds/userapps/release/tcs/common/scripts/power_adj_scripts/ring_heater_schedule.py ITMX -s "now" -d 4 -p 1[CTRL] + [B] and then [B]CO2X and CO2Y: We tried turning on CO2 central heating to reverse the effects of the RH as we couldn't lock DRMI. The TCS_ITMX/Y_CO2_PWR guardians are still not ready for prime time. The CO2 power calibration isn't correctly accounting for the masks so the guardians are complaining and I'm not sure how integrated into the ICS_LOCK guardian these are so far. ITMY looked flat (compared to cold IFO) after ~15minute at 0.8W central CO2, ITMY took more like 30minutes at 1.5W. Now I've paused both TCS_ITMX/Y_CO2_PWR guardians and changed both back to annular masks. Everything is now be back to normal.