gabriele.vajente@LIGO.ORG - posted 16:19, Sunday 23 April 2023 - last comment - 21:45, Sunday 23 April 2023(68931)
PRCL and CHARD signal noise over thermalization
The attached plot compares the CHARD and PRCL signals at the beginning of the lock and at intervals during 3 hours:
- PRCL_IN1 becomes lower as PRCL optical gain is lost
- PRCL_OUT also becomes lower, since the UGF servo adjustes the gain after PRCL_OUT. After 3 hours, the UGF servo has increased the gain by about 3.7
- CHARD_P imrpoves since the HAM1 FF is tuned for a thermalized IFO
- CHARD_Y becomes much noisier below 30 Hz, but there is no increase of coherence with PRCL
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Comments related to this report
Coherences of CHARD_Y in the noisy condition (3 hours in lock) vs less noisy (beginning of lock)
The increased noise in the 5-20 Hz region is due to... HAM1
Images attached to this comment
Trained new FF filters from HAM1 to CHARD_Y, PRC2_Y, INP1_Y and DC1_Y.
Some improvement in all signals, except DC1, so I turned off the DC1_Y FF.
Images attached to this comment
PR3 damping and IM1 damping dominates the low frequency motion in CHARD_Y