KAGRA Logbook

Reports 1-1 of 1

VIS (OMM)

takafumi.ushiba - 20:50 Friday 21 June 2024 (30052)

Health check of OMMT1

I performed OMMT1 health check.
Figure 1-7 show the TFs from each DoF.

Compared with the TFs in 2023 (klog25967), H3 to H3 transfer function (fig6) looks strange (we can see only small L resonant peak around 0.95 Hz though there was clear peak before).
I have no idea what happens.

Note:

Though measured TF phase is same as before, the definition of actuator sign is completely opposite from the nominal one.
Nominal sign actuator should push the suspension when IN1 at COILOUTF is positive.
Since OSEM value becomes larger when suspension is pushed from the coil because OSEM flag is pulled out, phase from each coil to each OSEM should be zero at DC.
So, it is necessary to flip the sign of COILOUTF gain to be actuator sign as a nominal ones.

Images attached to this report

30052_1718969381_Screenshot from 2024-06-21 20-25-54.png

30052_1718969384_Screenshot from 2024-06-21 20-26-03.png

30052_1718969387_Screenshot from 2024-06-21 20-26-13.png

30052_1718969389_Screenshot from 2024-06-21 20-26-23.png

30052_1718969391_Screenshot from 2024-06-21 20-26-34.png

30052_1718969393_Screenshot from 2024-06-21 20-26-43.png

30052_1718969396_Screenshot from 2024-06-21 20-26-56.png

Comments to this report:

ryutaro.takahashi - 20:29 Thursday 14 November 2024 (31637)

[Ushiba, Takahashi]

We went to a health check of OMMT1 suspension.
Figures 1-7 show the TFs from each DoF.

Since the H2 OSEM has glitches, the TFs using the H2 signals were not measured well. Compared with the TFs measured last time, the DC gains were reduced by -10dB, -8dB, and -6dB in the H1, H3, and H4 TFs respectively. This is due to the OSEM positions being far from the optimal position.

Images attached to this comment