Following the procedure discussed at the commissioning meeting we proceded with the optimization of the north arm matching with the new PR HR power.
We did the following steps:
- 1336842894 17 May 2022 17:14:36 UTC L1z -25.000 (backward)
- 1336845574 17 May 2022 17:59:16 UTC L1z -25.000 (backward)
- 1336847533 17 May 2022 18:31:55 UTC L1z -25.000 (backward)
- 1336849469 17 May 2022 19:04:11 UTC L1z -15.000 (backward)
- 1336851939 17 May 2022 19:45:21 UTC L1z -15.000 (backward)
- 1336853947 17 May 2022 20:18:49 UTC L1z +20.000 (forward)
The evolution of 02 modes and the area below (i.e the mismatching) are shown in pic. 1 and 2 respectively.
Then we switch ON the CH on the west at the power used for compensating the YAG (~150mW). The plan was to continuolsy scan the modes TEM2 and TEM1 to check both alignment and mismatching, but west green was unstable and unlocked few times (possibly due to a too fast CARM SET scan). Consequently we decided to scan only around TEM2.
A comparison of the modes during the thermal transient is shown in pic 3.
As we can see, during the thermalization the west arm matching passes through the minimum after more than 15 minutes of CH heating, and then it increases again. We kept scanning the TEM2 mode also during the cooling down after having switched off the WI CH. Data will be further analized offline.
A detailed list of scans and actions performed is in the attached .txt file (see also fig 4)