[Yong-Xiang Yang, Chia-Hsuan Hsiung, Gui Chin Liu (from Tamkang university), Chia-Jui Chou, Yuzurihara]
We performed the lockloss investigation for the lockloss from OBSERVATION_WITH_LINES in the recent data. We checked the data by using ndscope and Pastavi. We found some oscillation started before the lockloss. Ushiba-san already reported the oscillation issue in the klog. But, the frequency seems to be different.
Details
- The generated plots were collected on wiki.
Oscillation issue
- 2025-01-22 01:59:32 UTC
- We saw the oscillation at ETMX yaw with ~1.1 Hz. (Fig) The amplitude started to grow at the 30s before the lockloss. This trend can be seen in the ASC controls, ITMX yaw, ETMX yaw, and ETMY pitch. (Fig) (Fig) (Fig)
- The cause of the
- 2025-01-20 14:03:44 UTC
- We saw the oscillation at ETMX yaw with ~1.1 Hz. (Fig) (Fig) The amplitude started to grow at the 60s before the lockloss, in ITMY yaw, ETMY pitch, ETMY yaw, ITMX yaw, and ETMX yaw. This trend can be seen in the ASC controls.
- 2025-01-20 12:42:02 UTC
- We saw the periodic drop in the GRX, IRX, and IRY. The time of the drop is coincident with the ETMX yaw and ITMX yaw. (Fig) The fluctuation of ITMX yaw, ETMX yaw, and ETMY yaw is more than 1 urad is large compared with the normal operation. (Fig)
- 2025-01-19 02:11:54 UTC
- We saw the periodic drop in the GRX, IRX, and IRY. The fluctuation of ETMX yaw and ETMY yaw is more than 1 urad is large compared with the normal operation. (Fig) (Fig)
