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Entry  Fri Nov 12 14:31:38 2021, Stephen, Radhika, DailyProgress, Cryo vacuum chamber, Radiative Cooling of Si Mass, with better shield emissivity IMG_2738.jpegIMG_2741.jpegIMG_2742.jpegIMG_2745.jpegIMG_2747.jpeg
    Reply  Fri Nov 19 14:01:40 2021, Stephen, Radhika, DailyProgress, Cryo vacuum chamber, Radiative Cooling of Si Mass, with better shield emissivity comp_cooldown_728_cooldown_1116.pdf
    Reply  Fri Dec 10 15:58:57 2021, Stephen, DailyProgress, Cryo vacuum chamber, Radiative Cooling of Si Mass, with worse inner shield inner surface emissivity 
       Reply  Thu Dec 16 15:54:44 2021, Stephen, Radhika, DailyProgress, Cryo vacuum chamber, Radiative Cooling of Si Mass, with worse inner shield inner surface emissivity - CTC100 temperature control success cooldown_12-10_all.pdfcooldown_12-10_vs_11-16.pdf
          Reply  Tue Dec 21 15:33:39 2021, Stephen, DailyProgress, Cryo vacuum chamber, Radiative Cooling of Si Mass, with worse inner shield inner surface emissivity - next run repeating 
             Reply  Wed Dec 31 15:59:59 1969, Stephen, DailyProgress, Cryo vacuum chamber, Radiative Cooling of Si Mass, with worse inner shield inner surface emissivity - retry run was successful cooldown_12-21_vs_12-10.pdfMegastat_Heat_Load_Sketch.png12_21_cooldown_fit.png
Message ID: 2704     Entry time: Tue Dec 21 15:33:39 2021     In reply to: 2702     Reply to this: 2705
Author: Stephen 
Type: DailyProgress 
Category: Cryo vacuum chamber 
Subject: Radiative Cooling of Si Mass, with worse inner shield inner surface emissivity - next run repeating 

I opened the QIL cryostat today for a health check and visual inspection before the next run. Because I saw a couple of interesting issues, I decided to redo the same run with more attention to detail on the closeout. I'm worried the outer shield may have been linked to the inner shield and baseplate enough to affect comparability with the prior run.

issues with this  run, requiring redo:

  • RTD wire for outer shield was clamped under lid of inner shield - this might have created a conductive link between the inner shield and the outer shield
  • outer shield was more wobbly than usual, and could have possibly been off of the three spacers - this might have created a conductive link between the outer shield and the baseplate

run details:

  • pumping started at 3:45 pm
  • turbo started with 15 minute delay at 20 torr
  • cryocooler started at 4:15 pm with active ion gauge pressure at 3 e-4 torr.

And since I didn't get to implement any of the intended next runs, here are some notes on other future runs of interest:

  • Si mass covered with Al foil (matte side facing out) - interested in making the emissivity of the test mass equal to that of the inner shield in the new config, for modeling.
    • (of course, this emissivity equivalence would be an approximation, as there is a large area of the test mass which is bare silicon)
  • outer shield clamped/resting on baseplate - this is predicted by Koji to be the most efficient cooling configuration.
  • shielding attached to structure holding Si mass (electropolished aluminum, aquadag aluminum, bare aluminum surfaces are all available.
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