INJ recovery continued on Friday, after Thursday problems with DSP card. The final status is (details later here): INJ locked from Friday evening, RFC locked, PSTAB working, Fmoderr tuned and AA in drift control. The system appears to be stable overnight with the exception of three short fast unlock (see fig.1). On Monday, we will test the automatic alignment in full bandwidth.
After the problem with MC suspensions we started back the alignment by closing BPC loop. We then looked for a MC_F0_Z position close to RFC TEM00 and tuned fmoderr to 0. Checking the RFC phase, we remarked a strong phase shift of the error signal of the RFC (fig.4) then we correctly tuned it (fig. 5).
Then, recovering the position of IB bench and MC to last alignment in which AA was working (49402) brought the system in an unstable state (i.e. Tx/Ty of both MC and IB showed wide oscillation). Those oscillations were probably preventing AA system to work properly. We decided thus to move toward another previous position of IMC alignment by tuning directly the beam position on the MC_Cam (see fig. 2 and 3). Once the position finely tuned maximizing IMC_TRA and optimizing reflection, oscillations in Tx/Ty (in particular Tx for MC) were strongly reduced. Finally, we manually brought to 0 in ACL the offsets in tx/ty/tz error signal for both IB and MC.
After that, we measured again the sensing matrix with AA and RFC loops open, by injecting noise (a line at 2 Hz) on each AA DoF (see table below):
|DoF ||GPS |
|MC ty ||1284484080.00 |
|IB ty ||1284483757.00 |
|MC tx ||1284483974.00 |
|IB tx ||1284483680.00 |
|IB tz ||1284483835.00 |
In addition, to test the correctness of the new matrix, we individually tested again each degree of freedom by injecting noise, and verified that only the relative reconstructed error signal was acting.
We left AA loop in drift control.
- check offsets on galvos
- check phase modulation of QD FF/NF
- close IBz loop
- close AA loop on full bandwidth