Yesterday, we started the procedure (entry here) to increase the power in transmission of the IMC. Its power was around 23.7W and the idea was to increase it until 40W (an increase of 60%). We followed the steps described below:

- First, we measured the Transfer Function of the IMC. The UGF is 178 kHz.

- Then, we alligned the Power Recycling in order to take as reference the signal SIB2_B2_DC. In order to put this photodiode in security, we reduce its value from 20mW to 12.5mW (after the power increase it should return to the same value as before).

- The next step was to perform the transfer function of the PSTAB in EEroom (thanks to Jean-Pierre Coulon who helped us). Its UGF is around 100 kHz.

- We opened the BPC, the AA and the RFC loops.

- With PMC locked we measured the power in transmisstion of the IPC, which was 32W (corresponding to 23.7W in IMC_TRA).

- Then, we relocked BPC and IMC AA.

- We turned the rotator on the EIB to increase the power at the input of the IMC (rotator in the Electronic Injection Room EIB IPC axis 1 channel 1). We increased the power to its maximum value achievable, which was 30.2W (see attached plot).

- We adjusted the power in INJ_IMC_REFL_DC (rotator IPC8 axis 2 channel 1 in the Electronic Injection Room) in order to match it with the previous one (0.22W with IMC locked).

- We remeasured the power in transmission of the IPC and it was 40.8 W.

Today, first thing we did was to replace the gas bottle of the EIB that was already finished. Then, we started to realign the BPC by hand, which was very difficult beacause we were quite far from the right position. We then closed the loop of the BPC.

We also remeasured the power in transmission of the IPC and today we had 45.3W (different power meter from yesterday). This raise of power w.r.t yesterday was probably due to the fact that the EIB was in a bad position since the gas bottle was empty, therefore the beam could be clipped somewhere.

Then, we recovered also the alignment of the MC by hand, doing small steps with the Tx and Ty of the End Mirror of the MC and Tx, Ty and Tz of the bench. When we finally got a nice position, we locked the IMC AA in drift control and RFC (see image attached).

INJ will be left in this configuration for the weekend.