Virgo Logbook

Reports 1-1 of 1

Injection system (General activities)

genin, cleva, coulon, kefelian - 14:53 Tuesday 11 September 2018 (42674)

Injetcion system relocked after the night intervention.

After the PSL work of last night it took a few hours to recover the whole injection system mostly because there was a large offset on the PMC error signal.

We have not yet understoof the orgin of the problem but we could null this offset by shifting the 14MHz modulation frequency from 14.230MHz to 14.5MHz.

Maybe a cable length in the PMC loop has been changed?

When the PMC has been relocked we noticed a loss of roughly 5% with respect to yesterday. We have still to understand the origin of that loss. Part of that could

be related to the laser amplifier. Further investigations are needed.

In any case we could close all the injection system loops without any problem.

We may need to realign the PMC in the coming hours/days to recover misalignment related to thermal transients.

Comments to this report:

Cleva, Coulon, Pillant, Genin - 17:53 Tuesday 02 October 2018 (42881)

After the work around the slave laser loop and offsets related we notice that curing the slave error signal offset has no effect on the PMC error signal offset.

We find a further optimization of the residal PMC offset moving from 14.50 MHz to 14.53 MHz. This optimization was visible on the PMC_TRA

cleva - 17:59 Tuesday 02 October 2018 (42882)

see 42865 as a possible explanation of the loss after the PMC