ITF found during locking acquisition. During the first part of the shift the ITF kept unlocking at various stages (see attached plot #1) with the most succesful one reaching LOW_NOISE_2.
At 19:42 UTC the ITF reached LOW_NOISE_3_SQZ, and was set in Science Mode.
ITF left locked.
Guard Tour (UTC):
17:00 - 17:31
19:30 - 20:02
Today the ITF unlocked continuously along different step of the acquisition, the few times it was able to go towards the final steps of the acquisition (Low Noise 2), it unlocked sistematically due to the 400 mHz oscillation, well visible in the fringe, which became too bright. This oscillation seems affecting BS TX, which starts to oscillate up to divergence right after the switch of the control loop to 'full bandwidth'. This has an effect also on SDB1 detection bench, along TX (Fig.1).
For the time being, the engagement of the full bandwidth mode in LN2 has been commented (line 5862 ITF_lock.py).
The ITF keeps unlocking in different places -> microseism and wind activity (not high since this late morning) in the decreasing phase (Fig.2).
400 mHz still quite high with rescpect to yesterday (Fig.3).
Several unlocks at CARM null 1f not clear...will be better investigated.
Since we observed some unlocks due to glitches on the local controls of the BS (engaged in drift since the 27th), see for ex. plot 1 and 2, yesterday we restored the engagement of the full bandwidth in LN2 for the BS TX. The ITF kept the lock all the night (#5862 ITF_lock.py).
