KAGRA Logbook

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VIS (EY)

yoshinori.fujii - 13:48 Thursday 20 June 2019 (9293)

F3, BF-V sensor porality was changed

= ETMY =

I found that F3-GAS was alive, it is now free, based on a transfer function measurement, Fig 1.
- The GAS position where the F3 is alive is in Fig 2.
- The measured transfer function is in Fig 3.
- So far, the actuation amplitude looked large.
- the measurement files are in /users/VISsvn/TypeAtower/ETMY/Measurements/TF/Measurements/20190620/.
During the work, I found that the sensor polarity of F3 and BF-V was opposite with F0-GAS (ref: klog#8553).
- The sensor polarity of F3 and BF-V1/V2/V3 was changed and now they are:
  - F3: 0.612
  - V1: -0.409
  - V2: -0.439
  - V3: 0.385
- The coil polarities were changed accordingly, Fig 4.

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Comments to this report:

yoshinori.fujii - 17:45 Friday 21 June 2019 (9308)

FYI, the trend of GAS keystone position is attached. It seemed that F3-GAS have been at the current position from about June 7th 2019 though, it seemed F3-GAS was free from like February 2019.. Who said that the F3-GAS was not working?

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