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Injection system (General activities)
gosselin, derossi, genin, pillant - 18:37 Wednesday 14 November 2018 (43577) Print this report
PMC transmission optimization and IMC AA matrix retuning

This morning, there were some troubles in the lock acquisition. While reaching the SSFS boost step the IMC was unlocking. This must be due to the conversion of the additionnal frequency noise into power noise of the PMC that we were investigating yesterday (entry 43562 )

We went into the laser lab to realign the PMC and set the modulation frequency to readjust its working point: from 14.56 MHz to 14.53 MHz. The transmission of the PMC went from 0.84 V to 0.91V.

Then we retuned the offest on the IMC_REFL galvos. The new values are given below:
ACL_CONST_CH NF_H_offset "V/V" 1 LOOP_FREQ 0.05
ACL_CONST_CH NF_V_offset "V/V" 1 LOOP_FREQ 0.02
ACL_CONST_CH FF_H_offset "V/V" 1 LOOP_FREQ 0.35
ACL_CONST_CH FF_V_offset "V/V" 1 LOOP_FREQ -0.05

We finally remeasured the matrix of the IMC AA:

AA. ACL_MATRIX_BEGIN sensing_matrix 1 MCT_hNORM FF_ACh NF_ACh MCT_vNORM FF_ACv NF_ACv
ACL_MATRIX_CH MC_ty_err "" 12.57 0.00 -1.72 0 0 0
ACL_MATRIX_CH IB_ty_err "" 20.56 0.00 -22.09 0 0 0
ACL_MATRIX_CH MC_tx_err "" 0 0 0 6.29 17.81 -8.12
ACL_MATRIX_CH IB_tx_err "" 0 0 0 34.30 19.06 -8.69
ACL_MATRIX_CH IB_tz_err "" 0 0 0 10.45 2.44 29.62
ACL_MATRIX_END sensing_matrix

The noise injections to define the matrix have been done with the SSFS locked instead of the RFC locked as it was done before. Thus the AA is less sensitive while reaching this step of the lock acquisition. The lock has been relocked in low noise 3. There are still a lot of coupling of the frequency noise to the IMC AA error signal. This would deserve more work.

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