KAGRA Logbook

Reports 1-1 of 1

VIS (SR2)

kenta.tanaka - 14:07 Tuesday 23 January 2024 (28369)

Health check of SR2

I checked the TF results in Fig. 1 - 28. I wrote down what I noticed as follows.

## IP

COIL H{1,2,3} -> LVDT H{1,2,3}: seem to be healthy
COIL H{1,2,3} -> ACC H{1,2,3}: Current TFs completely differ from the references. However, references seems to see just the noise originally.
TEST L -> IDAMP L, TEST T -> IDAMP T, TEST Y -> IDAMP Y : seem to be healthy, each noise in the higher freq. region improved.
The couplings from one DoF to the other DoF, especially {L, T} -> Y seem to change.

## GAS

All of the lowest resonant frequencies got lower slightly.
The highest resonance peak in F0 -> F0 and F1 -> F1 seem to be damped. This maybe cause that the highset resonance peaks in their couplings seem to be damped.

## IM

COIL H{1,2,3} -> OSEM H{1,2,3}, COIL V{1,2,3} -> OSEM V{1,2,3}: seem to be healthy.
The 0.227 Hz peak in the couplings in H2 -> V{1,2,3}, H3 -> V{1,2,3} got bigger to +20dB.
The 0.148 Hz peak in the coupling in V1 -> H2, H3 got smaller to -20 dB.
The DC gain in the coupling from V2 to H2 got smaller to -20dB.
The shape of the coupling from V3 to H1 seems to change.
TEST {L,T,R,P,Y} -> DAMP {L,T,R,P,Y} seem too be healthy.
The bump appears around 0.2 Hz in TEST V -> DAMP V maybe because the 0.227 Hz peak in the coupling H2 and H3 to V{1,2,3} got bigger.
Some peaks in TFs from L to T, V, P, R, Y seems damped.

## TM

COIL H{1,2,3,4} -> OPLEV {L,P,Y} seem to be healthy.
TEST {L, P, Y} -> OPLEV {L, P, Y} seem to be healthy.

Images attached to this report

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Comments to this report:

ryutaro.takahashi - 15:40 Tuesday 14 May 2024 (29498)

I checked the TFs measured in air. They look healthy. There were some differences from the reference.

IP: L-T-Y coupling was changed. S/N of the measurement was improved at high frequencies.
GAS: The frequency of the lowest mode was shifted to the low frequency. The Q of the third mode became low.
TM: The gain from L/H3 to L was larger than the reference a little.

Images attached to this comment