sheila.dwyer@LIGO.ORG - posted 21:48, Monday 20 August 2018 - last comment - 01:59, Thursday 23 August 2018(43543)
ITMX bounce mode
We have seen one of our bounce modes, which we hadn't seen until today since the installation of the bounce mode dampers.
The mode we see is at 9.726Hz, and seems to be ITMX.
Jim W suggested that ITMX might be the problem since the suspension was left damped overnight while the ISI was isolated, which we know causes problems. I tried the same phase as the O2 damping: -90 degrees, gain of 1
This bounce mode appeared again tonight, and is ringing down without any active damping.