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Entry  Fri Jan 7 14:54:58 2022, Stephen, DailyProgress, Cryo vacuum chamber, Fastest Radiative Cooling run started 14 Jan 
    Reply  Tue Jan 18 16:11:35 2022, Stephen, DailyProgress, Cryo vacuum chamber, Status of Fastest Radiative Cooling run started 14 Jan 5w_input_qil_cryostat_20220119.png5w_input_121_to_145_hours_qil_cryostat_20220124.png
Message ID: 2706     Entry time: Fri Jan 7 14:54:58 2022     Reply to this: 2708
Author: Stephen 
Type: DailyProgress 
Category: Cryo vacuum chamber 
Subject: Fastest Radiative Cooling run started 14 Jan 

As discussed during the 07 Jan 2022 meeting, the next cryostat run will seek the fastest radiative cooling through the following configuration choices:

  • eliminate radiation leak apertures
  • maximize emissivity of test mass volume
  • improve conductivity to outer shield

Actions completed 14 Jan 2022

  • Vent
  • Cover up aperture to viewport with foil (on both shields).
  • Remove foil from inner shield inner surface.
  • Place outer shield directly onto cold plate (no clamping force).
    • A bit unsatisfying, because the outer shield is not flat relative to the cold plate, but the shield is resting quite firmly with only a slight wobble when pressed. As with any plane-plane contact, there are a limited number of true points of contact, and the contact area is increased somewhat by foil that is folded around the outer shield or the cold plate.
      • I would estimate the contact area at ~5% of the total area of the bottom flange.
    • 2x G10 spacer washers were dropped into the lower volume whild making this switch.
    • Note that bottom lid of outer shield is still not conductively cooled, and therefore will be approximately room temperature.
  • Tidy up aluminum foil collar around bottom lid of outer shield.
  • Tidy up mylar shield around conductive link after inner shield
  • Pump down, cool down.
    • Pump down started at ~15:35.
    • Cool down started at 16:10.
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