Alexa, Kiwamu
In response to the commissioning alog from the last night (alog 16501), we spent an hour or two to study the DRMI lock acquisition with ETMs miasliged in this morning. The key item we checked this time was the BS limiter. We took a few lock acquisition samples with and without the BS limiter which was suggested by Ryan.
It seems that the limiter improved the locking time. We will tentatively keep the limiter on.
The alignment was adjusted initially so that we observed consistently high build up in each lock. We tried repeating the same test with the arm cavities aligned, but we ran into some aligment issues which prevented us from completing the test with the arm cavities aligned. Note that this limiter method is something we used to use in the past, but apparently we decided not to use it for some reason at some point.
(The test without the limiter)
time to lock [sec] | |
attempt #1 | 10 |
#2 | 120 |
#3 | 540 |
#4 |
270 |
(The test with the limiter)
time to lock [sec] | |
attempt #1 | 5 |
#2 | 120 |
#3 | 60 |
#4 | 80 |
#5 | 90 |
(The limiter)
The limiter resides in BS_M3_ISCINF_LIMIT and the value was set to 5x105 cnts.
This limiter was being engaged during lock aquisition and then turned off when lock was aquired during the MICH_DARK_LOCKED state of the LSC_CONFIGS gaurdian. However, none of this was translated over to the ISC_DRMI guardian. I have added this to the ISC_DRMI guardian now.