Tonight's shift didn't see any major improvements w.r.t. yesterday, as the ITF was less stable and the PRITF configuration was more affected than usual by glitches and oscillations; as we didn't get any further than MICH_SET = 0.3, rather than pushing with repetitive trials we focused a bit on some 'side' things:

• we began implementing a CARM_SLOW loop, which uses the RFC error signal once it is out of loop (i.e. when CARM is controlled with the Mode Cleaner) and corrects at low frequency; this is still a first implementation and the filter can surely be optimized, but it is promising. In Figure 1 you can see some minutes of data of our test; for this purpose there is a new CARM_SLOW_on() function in the LSC_init.py script. Note that it is already implemented in the CARM_DARM_LOCK node as a possible follow-up state, but I have to integrate it in ITF_LOCK once we decide the best moment to engage the loop. The LSC_Acl process already takes care of resetting everything in case of an unlock;
• we did a new TF measurement of the DARM, MICH and PRCL loops in the PRITF configuration at half fringe (Figures 2 to 4), with the new driving matrix for the decoupling of MICH and PRCL; while PRCL and DARM do not show any issue, we can still see the shrinking of MICH's phase bubble when the PRCL loop is closed.

I leave the ITF in the Recombined configuration.