KAGRA Logbook

VAC (OMC)

nobuhiro.kimura - 15:45 Monday 18 November 2024 (31673)

Bellows duct connection between OMMT~OMC and start of vacuum evacuation

[Kimura, Yasui, M. Takahashi, H. Sawada and Nakajima (MIRPRO)]

On the morning of Nov. 18, we conneted a bellows duct between the OMMT and OMC.
Then, we cloased two side flanges and two K-400 flanges.

The elastomer seals of the flange connections were reused.
The claw clamps were tightened by increasing the tightening torque in steps of 20 and 40 Nm.

After the closing work for the flanges, we started of vacuum evacuation by dry pump at 11:31.

Then we started of vacuum evacuation by TMP at 14:20.

The gate valve between SR3 and SRM is currently closed.
The gate valve between SRM and OMMT is open.

Comments to this report:

nobuhiro.kimura - 11:50 Tuesday 19 November 2024 (31681)

[Kimura and Yasui]
At 10:00 AM on Nov. 19, we opened Gate Valve between SR3 and SRM.
Before opening the gate valve, the switch from TMP to ion pump was performed, but the pressure was not stable and reached 1x10^-3 Pa.
Therefore, vacuum pumping by TMP was continued and Ion pump was stopped.
The FFU and SR-C air conditioning system were shut down.
　We also reduced the number of the operating FFUs at SRM, SR3, and OMC.
The number of FFUs at SRM and SR3 is 2.
The number of FFUs at OMC is 1.

nobuhiro.kimura - 14:53 Tuesday 19 November 2024 (31686)

[Kimura, Yasui, M. Takahashi, H. Sawada and Nakajima (MIRPRO)]
During the duct fastening process, we found a working light left on the optical table inside the OMC vacuum vessel.
Therefore, we removed the light and inspected the area for other tools in the vacuum vessel .
Other than the lighting, no other items were found to be left inside the vacuum vessel.
It is necessary to check for any remaining items after the work in the vacuum vessel is completed.

nobuhiro.kimura - 15:49 Tuesday 19 November 2024 (31689)

[Kimura and Yasui]

We turned on the Ion pump of SRM vacuum pump unit at 15;30.

Currently, the ion pump and TMP of the SRM vacuum pump unit are operating simultaneously to continue pumping.

takashi.uchiyama - 11:02 Wednesday 20 November 2024 (31695)

2024/11/20

Kimura, Uchiyama

We closed the GV in front of TMP at SRM to see if the ion pump can keep the vacuum pressure at SRM.

Vacuum pressure at SRM was 4.3e-5 Pa before closing the GV. 1 hour after closing the GV, vacuum pressure increased and reached 1e-4 Pa.
We discussed the situation and decided to use TMP continuously.

We opened the GV at around 10:50 and the vacuum pressure recovered again.