This morning I ve changed in LN3 the setpoint for NI Y. The overall stablity of the lock has been worsened by the decentering and the behavior was not showing a good direction.
Y positive:
- MICH offset reduced
- B1p increased
- B7 & B8 increased
- DIFFp TX set increased
Y negative opposed behavior but in both directions the ITF stability was worsened
Exploring beam position in LN3 is very slow and inconvenient. From what I remember of past tuning the speed at which the rest of the control loop reacts limit the tuning to 1mm per hour (https://logbook.virgo-gw.eu/virgo/?r=65985). In CARM NULL 1F the response is much faster, and one can do changes on a time scale of 10 minutes instead of one hour. So this type of checks should be done in CARM NULL 1F not in LN3.
