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VAC (General)
takaaki.yokozawa - 3:56 Tuesday 29 November 2022 (23065) Print this report
Vacuum level IX increased
The vacuum level of the IX area increased gradually.
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shinji.miyoki - 11:32 Sunday 04 December 2022 (23118) Print this report

This increase seems to start after klog#22470 on Oct 13th (Fig.1). Because much H2O can go to the IX/IY area from the MICH area, we can expect some amount of temp increase.

In the IX area, the temps of, at least, the 4K-ref*-50K-bar/head and arm/BS-side-radiation shield are increasing in the same manner (Fig2).

The IY area shows the same temp enhancement around Oct 13th. However, after that, the temps are roughly constant for the 4K-ref*-50K-bar/head and "BS-side-radiation shield". While finally?, the temp of the arm-side-radiation shield seemed to slightly increase(Fig3).

 

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shinji.miyoki - 8:27 Tuesday 06 December 2022 (23135) Print this report

The IXA pressure level might show a trend change?

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shinji.miyoki - 8:41 Wednesday 07 December 2022 (23152) Print this report

It keeps decreasing.

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nobuhiro.kimura - 15:24 Wednesday 07 December 2022 (23155) Print this report
As the attached graphs show, the downward trend in pressure is supported by the residual gas measurements in the IXC.
The residual gas component that increases or decreases is mainly water molecule (H2O).
The source of this component is assumed to be degassing from the duct shield surface and the Super Insulation that surround it..

Based on the saturated vapor pressure of water and the temperature of the duct shield surface,
I (KIMURA) estimate that there is no further degassing.
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shinji.miyoki - 10:19 Saturday 10 December 2022 (23197) Print this report

IXA vacuum level once became ~5x10^-3 Pa and ~5x10^-5 Pa level around 9 am on 10th Dec. The temps of the duct shield are around 200~190K

We can open GVs, maybe.

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