KAGRA Logbook

With Yasui-san.

See notebook notes in album PR3 Remedying Work.

Last week we finished assessing the health of the in-vacuum cables by measuring resistances, inductances and capacitances at the outer side of the flanges of the vacuum chambers. We had unexpected results and in this entry I report the reproducibility after a second assessment. The ones of concern have an asterisk:

PR3, IM-V1 OSEM, P4-1, pins 2-7:
- Symptom: the measured resistance (18.6 Ohm) was higher than the equivalent resistance in other OSEMs (~15.8 Ohm).
- Reproducibility: today we measured 15.9 Ohm and it was stable. It seems there's no problem.
* PR3, BF-H3 LVDT, P2-3, pins 1-6:
- Symptom: the measured resistance (21.6 Ohm) is higher than the equivalent resistance in other BF LVDTs (~12.1 Ohm).
- Reproducibility: We confirmed this value and it's stable.
- Following step: we should open the chamber and take a look.
- Difficulty: likely, medium, because although the cables are relatively accessible, cabling is messy.
PR3, BF-V2 LVDT, P3-7, pins 2-7:
- Symptom: the measured resistance (14.015 Ohm) was higher than the equivalent resistance in other BF LVDTs (~12.1 Ohm).
- Reproducibility: today we measured 12.5 Ohm and it was stable. It seems there's no problem.
* PR3, BF-V3 LVDT, P2-1, pins 1-6:
- Symptom: the measured resistance (14.1 Ohm) is higher than the equivalent resistance in other BF LVDTs (~12.1 Ohm).
- Reproducibility: We confirmed this value and it's stable.
- Following step: we should open the chamber and take a look.
- Difficulty: likely, medium, because although the cables are relatively accessible, cabling is messy.
PR3 F1 stepper motor, P3-3:
- Symptom: the resistances of both coils are higher than expected (14.5 Ohm vs. 8 Ohm).
- Reproducibility: we measured 8.3 and 8.6 Ohm and these values are stable. It seems there's no problem.
PRM, BF-H2 LVDT, P3-3, pins 2-7:
- Symptom: the measured resistance (13.5 Ohm) was higher than the equivalent resistance in other BF LVDTs (~12.1 Ohm).
- Reproducibility: today we measured 12.8 Ohm and it was stable. It seems there's no problem. This value is the highest of this type of coil, with the second highest 12.6 Ohm.