I ran the automeasurement script for ETMX health check.
Though the detail should be checked carefuly, one of the TM magnets (H1) might be fallen off according to the quick health check result (fig1).
Figure 2 shows the H2 measurement result for your reference.
To confirm the healthiness of TM H1 magnet, I tried to excite 7.5 Hz pitch resonance with H1 actuator.
Even if applying 20000 cnts to H1 coil, almost no excitation can be seen at resonant frequency while we can easily excite the resonance by using H2 coil with 1000 cnts excitation signals.
So, H1 magnet does not work well.
I checked all TFs of ETMX (fig1-50)
Followings are what I noticed.
1. Q value of lowest mode when exciting IP H1 seems smaller than before. Since IPL/IPT measurement seems fine, it seems just the variation of the measurement.
2. Q value of lowest mode when exciting GAS filters seems smaller than before. I'm not sure the reason.
3. Notches between resonances when exciting BFL seems small. I'm not sure the reason.
4. Coherence between 0.1-1 Hz is bad in some measurement results of BF. Slightly rubbing somewhere? It is better to remeasure them after offloading tower part.
5. Coherence when IMY excitation is low at high frequency. It is better to check it again.
6. Coherence when exciting IM H1/H2/V1/V2 is low at high frequency.
I measured all TFs of EULER and COIL DoFs of ETMX.
Attached figure show the result.
TFs seem healthy except for the vertical DoFs of tower part.
I cannot judge what happens on the GAS TFs, Takahashi-san wil report them.
Photosensor gain change is due to efficiency difference at room temperature and cryogenic temperature, so no matter.
MN roll TF have slightly fast phase rotation at high frequency.
I checked in-air TF measurement result before O4a but due to the low coherence at high frequency, it is hard to say there is a phase delay.
Also, I checked in-air TF measurement of ITMY before O4a, and the result has a similar phase delay.
So, one possibility is differene between in-air measurement and in-vac measurement.
Another possibility is coupling due to CRY stepper motor, which is now turned on for alignment but not in the previous measurement.
Anyway, roll control will be handover to MN OpLev signals in LOCK_ACQUISITION state, this phase delay doesn't affect the damping performance, lock acquisition, sensitivity, and so on.
I compared the measured GAS TFs with the models in the case of 0.6-Hz resonance in BF. Each stage TF was almost consistent with the model.
