ITMX was oscillating at the 1urad level in pitch. I found the LVDT signal of the F3 GAS is strange. The F3 GAS started oscillations around 1Hz when the LVDT signal crossed the setpoint. I changed the setpoint from 554 to 560. Though the LVDT signal was still a little strange, the fluctuation became smaller.
Do you have any particular reason to increasing the set point value but not decreasing it?
In addition to this ~Hz level oscillation, it has also 0.04Hz (~25 seconds period) osccullation as Fig.1/2/3 just after the big earth recovery and yesterday.
IX F2 or F3 has also strange oscillation with very long period (~ 12 hours) as Fig.1 from 11days ago. If this is related with the tidal motion, why only this GAS is sensitive? Please check it. (Fig.1)
In addition, F3 still has an strange "excitation" at the level of 100 counts. (Fig.2/3)
EY GASs show strange oscillations maybe originated from F1 at the level of 1000 counts with ~ 30 minutes period. This oscillation seemed to exist over 1 year or more.
The problem of F3 GAS LVDT in 2022 might remain (klog).
0.04 Hz oscillation again. Because of this, the IFO could not lock again from midnight. (Fig.1, 2)
In addition. F3 lower position seemed not to be proper. Upper positiom is desirable to avoid this oscillation. (Fig.3, 4)
Fig.5 shows the temperatures in KAGRA. No remarkable temperature changes around IXYC with 0.1C resolution. So this GASs drift shows the slight temperature reduction around IYC less than 0.1C level.
In the same manner, how about lift up IX F2 to avoid 12 hours oscillation.
[Miyoki, Ushiba, Takahashi]
We found the IP was oscillating around 1Hz as well as the TM. We tried to change the setpoint of F3 from 560 to 570. The oscillation of TM/IP at 1Hz and the oscillation of F3 at 0.04Hz became small. Just in case, we changed the setpoint more to 654; in total +100 from Nov. 11. The setpoint of F1 was also corrected from -1533 to -1633. We understood the F3 keystone was possibly rubbing at the lower position.
The F1, F2, and F3 GAS filters were offloaded with the FRs.
Comments on "12 hours oscillation". The F0, F2, and F3 GAS filters have been oscillating at 12-hour intervals since Oct. 31. Such an oscillation is observed in the IPs. It would be due to the ground's tilt caused by tidal motion. I have no idea why the tilt couples to the vertical motion.
On 31st October, the CMS circuit was changed to the original one, which had 1/10 -> 10 times gain compensation. I just suspect some settings for the common mode servo triggered this 12-hours oscillation.