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Message ID: 2549     Entry time: Thu Apr 1 20:33:42 2021
Author: Stephen 
Type: DailyProgress 
Category: Cryo vacuum chamber 
Subject: Installation of Radiation Shields 

2021.03.17, StephenA

1. Radiation Shields located (in TCS lab), unwrapped, fitted up.

Location in TCS Lab - IMG_8351

Removed lid and placed adjacent to chamber (cleared a little space, used 3 plastic flange covers to make nonmarring surface safe for lid and o-ring - IMG_8353

Fit up as installed - IMG_8354

Comments on the fit up - I looked at all of the apparent sources for insights into Rahul's original design intent - QIL elog 2276, DCC T1800308-v1, wiki for Cryo Vacuum Chamber. It appears that Rahul never decoupled the upper outer radiation shield from the cold plate, which seems like a strange omission. Chris and Raymond also appear to have been wrapping their heads around the intended layout, they came up with the fit up in QIL elog 2429 and sketch from QIL elog 2430. I will revisit their sketch at a future opportunity, but I went with something closer to 2429 as I was concerned about the height misalignments they described. Note that the height misalignment appears in Rahul's T1800308 CAD (see T1800308-v1 screenshot) so who knows what's "correct". I'll work on finalizing D2100310 CAD with radiation shield to capture the true current dimensions and fit up, to hopefully avoid such issues in the future.

2. Radiation Shields installed in Cryostat. Sequence was important here, as were a couple of improvised solutions to shortcomings of the existing parts.

Dog Clamps placed on bottom plate (to stand off bottom radiation shield bottom lid; not pictured, I think I placed some alumina washers on the dog clamps as well, not sure though anymore!). Also pictured are the usual PEEK legs for cold plate - IMG_8355

Bottom radiation shield bottom lid placed on dog clamps spacer, and bottom radiation shield cylinder placed on bottom lid - IMG_8356. Seems likely that the bottom radiation shield would be better configured upside-down.

Bolted cold plate down onto legs, with cold plate decoupled from bottom radiation shield - IMG_8357

Outer radiation shield installed and inner radiation shield installed (both needed to be tipped into place gingerly, but both cleared the cold finger cylinder with the flange removed. The heater also passed through the apertures successfully - IMG_8358

2x Alumina washers placed under outer radiation shield, inner radiation shield on cold plate - IMG_8374

Cold Flange reinstalled, though one of the brass SHCS was sheared - this was due to over torque, with 20 in*lb applied by mistake. Correct torque is 10 in*lb. The remaining 3 bolts were tightened to 10 in*lb. - IMG_8360

Top view of radiation shield apertures and cold plate grid - IMG_8375

Thermal strap interface to cold plate - dog clamps required due to strange spacing of clearance holes. - IMG_8376



Attachment 1: IMG_8351.JPG  2.398 MB  Uploaded Thu Apr 1 22:15:51 2021  | Hide | Hide all
Attachment 2: IMG_8353.JPG  3.015 MB  Uploaded Thu Apr 1 22:16:10 2021  | Hide | Hide all
Attachment 3: IMG_8354.JPG  3.903 MB  Uploaded Thu Apr 1 22:17:15 2021  | Hide | Hide all
Attachment 4: t1800308-v1_cryostat_step_section_screenshot.png  198 kB  Uploaded Thu Apr 1 22:26:45 2021  | Hide | Hide all
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Attachment 11: IMG_8375.JPG  2.384 MB  Uploaded Thu Apr 1 23:42:05 2021  | Hide | Hide all
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