Similar work with klog19514 and klog19520.

Abstract:
Health check of 5 GAS filters were performed.
They doesn't seem to be changed from that at atmospheric pressures.
So, I made models of mechanical transfer functions based on the measurement.

Details:
Figure 1 to 5 show the suspension mechanical TFs from GAS excitations to GAS LVDT signals of F0, F1, F2, F3, and BF stages, respectively.
They are not changed significantly due to vacuum evacuation although we could see sprious couplings at high frequencies.

So, I made TF models.
Figure 6 to 10 show the models of GAS filters of F0, F1, F2, F3, and BF, respectively.
They are stored at FM10 (SUSMod_220114) of DAMP_GAS filter banks.
The models were based on the TFs measured on 14 of January, which are stored at /kagra/Dropbox/Measurements/VIS/PLANT/ITMX/2022/01/PLANT_ITMX_STANDBY_{F0,F1,F2,F3,BF}_TEST_GAS_202201141937.xml.