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Reports until 14:57, Tuesday 05 March 2013
LHO VE
john.worden@LIGO.ORG - posted 14:57, Tuesday 05 March 2013 - last comment - 17:05, Tuesday 17 June 2014(5666)
Y1 Beam Tube Module accumulation

Kyle valved out the Y1 Module for a few hours today. Tomorrow  we will valve out the Y2 module.

Attached is the rate of rise for the two end vacuum gauges.

If I have done the math correctly this translates to a very low outgassing rate with no significant leaks :  1.3 e-6 tl/sec for the 2km module. If it is all H2 this yields ~2e-14 tl/s/cm2

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john.worden@LIGO.ORG - 07:37, Wednesday 06 March 2013 (5673)

Rai reminded me that the gauge factor for H2 is about twice that for N2. So the outgassing rate stated above should be ~2x higher. Rai reports a number of 4e-14 for the H2 outgassing rate when measured 15 years ago.

 

john.worden@LIGO.ORG - 15:36, Wednesday 06 March 2013 (5685)

An accumulation on Y2 was performed today. See the attached plot.

The results are 2.4 e-7 tl/s for the module which translates to an H2 outgassing rate of ~6.6 tl/s/cm^2 (using a gauge correction of 2 for H2)

This is significantly better than Y1.

 

Also attached is a plot of the two accumulations plotted on the same time scale.

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john.worden@LIGO.ORG - 17:05, Tuesday 17 June 2014 (12401)

Correction: the number above should be 6.6 e-15 tl/s/cm^2 for the H2 outgassing.

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