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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: 2701     Entry time: Fri Dec 10 15:58:57 2021     In reply to: 2695     Reply to this: 2702
Author: Stephen 
Type: DailyProgress 
Category: Cryo vacuum chamber 
Subject: Radiative Cooling of Si Mass, with worse inner shield inner surface emissivity 

Started a new run this afternoon, with the following goals:

   1) confirm that the first run (QIL/2695) went smoothly, by performing a visual inspection in the chamber while setting up for the first run.

      - kapton tape affixing inner shield RTD lead junctions to inner shield had fallen. These junctions were simply hanging - not ideal, but apparently not too harmful. Not likely to impact temperatures, in my opinion, but could have led to shorts or glitches in data.

      - all RTDs appeared to be fixed and well-contacted to surfaces

      - Everything seemed to be in good shape with the copper bar, no apparent issues

   2) obtain a second run with similar configuration, now that the rigid copper bar linkage has been implemented.

   3) vary a single important parameter relative to the first run, namely the inner surface emissivity of the inner shield, so that the impact of that parameter may be observed.

      - Added Aluminum foil (matte side visible) to the inner shield inner surfaces (lid and cylinder, both). Anywhere there was previously black Aquadag, there is now matte aluminum foil.

      - Kept the same apertures for viewport access and for electrical and thermal connection passthrough, basically attempted to achieve identical shield coverage.

      - There is one small sliver of black aquadag visible at the location of the electrical leads, but I didn't worry about patching that small area.

Run Details:

   - Pumps on at  ~3:40 pm

   - Cooling started at 4:13 pm (pressure ~6 mTorr, rapidly falling with turbo pump spinning up from ~70% to ~85% over a 1 minute interval). Coldhead RTD is responsive.

   - All photos will be posted to the QIL Cryo Vacuum Chamber photo album.

   - Note from check in on Monday afternoon, ~ 69 hours after start: everything looks good, and the workpiece temperature (~127 K) seems to reflect the emissivity change.

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