In order to debug the recent problem of stability of the PSL/INJ system, we measured the TF of the PSTAB (fig. 1) and the error signal of the PMC loop (fig. 2).
At a first sight, we couldn't spot any strange behaviour of those part, but we will keep investiganting tomorrow morning.
During the night we left the PSTAB open and no INJ unlocks were observed.
We optimized the alignment of the beam in the AOM before the PMC (which is the actuator for the PSTAB. The beam must be close to the edge, see photo1), looking at the transmission of the PMC while scanning and minimizing the misalignment mode 01. To be noticed that there are strange structures close to the 01 (photo 2). An improvement can be observed up to 10Hz (plot 3).
Another test we would like to perform is to lower the chiller temperature setpoint for the Neovan head from 16° to 15°, but we didn't do it this morning to decouple from the alignment.
