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Message ID: 2645     Entry time: Sun Aug 15 00:33:15 2021
Author: Koji 
Type: Summary 
Category: Cryo vacuum chamber 
Subject: Aquadag painting on the inner shield 

[Stephen Koji]

We applied Aquadag painting on the inner side of the inner shield.

  • Upon the painting work, we discussed which surfaces to be painted. Basically, the surface treatment needs to be determined not by the objects but by the thermal link between the objects.
    • We want to maximize the heat extraction from the test mass. This means that we want to maximize the emissivity factor between the test mass and the inner shield.
    • Therefore the inner barrel surface of the inner shield was decided to be painted. The test mass was painted in the previous test.
    • For the same reason, the lid of the inner shield was painted.
    • It is better to paint the cold plate (table) too. But we were afraid of making it too messy. We decided to place the painted Al foil pieces on the table.
    • The outer surface of the inner shield and the inner surface of the outer shield: Our outer shield is sort of isolated from the cold head and the steady-state temp is ~240K. Therefore we believe that what we want is isolation between the inner and outer shields. Therefore we didn't paint these surfaces. (note that in Mariner and beyond, the outer shield will be cooled, not isolated, and the radiative link to the outer shield would be strong by design)
    • I believe that this is not the ideal condition for the inner shield. We need to model the cryo stat heat load and take a balance between the isolation and the conduction between the outer shield and the cold head so that we gain the benefit of the outer shield as a "not so hot" enclosure.
  • OK, so we painted the inner barrel of the inner shield, the lid of the inner shield, and some Al foils (shiny side).
  • Stephen made the Aquadag solution. The solution was 2 scoops of Aquadag concentrate + 6 scoops of water, and the adhesion/runniness test was done on a piece of aluminum foil.
  • The barrel and the lid were painted twice. Attachment 1 shows the painting of the inner shield cylinder. Attachment 2 shows a typical blemish which necessitates the second coat.
  • To accelerate the drying process, we brought the heat gun from the EE shop --> (update - returned to EE shop, see Attachment 3)
  • We took some photos of the process. They are all dumped in the QIL Cryo Vacuum Chamber Photo Dump album in the ligo.wbridge account.
Attachment 1: IMG_9636.JPG  2.463 MB  Uploaded Mon Aug 16 15:07:53 2021  | Hide | Hide all
Attachment 2: IMG_9632.JPG  2.719 MB  Uploaded Mon Aug 16 15:08:11 2021  | Hide | Hide all
Attachment 3: IMG_9646.JPG  2.422 MB  Uploaded Mon Aug 16 15:11:51 2021  | Hide | Hide all
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