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Entry  Mon Feb 7 11:57:38 2022, Stephen, DailyProgress, Cryo vacuum chamber, Doubled Thermal Linkage Capacity run started 11 Feb 2022 D2000310_y-004_section_double_linkage_20220207.png
    Reply  Tue Feb 15 11:59:22 2022, Radhika, DailyProgress, Cryo vacuum chamber, Doubled Thermal Linkage Capacity run started 11 Feb 2022 Cu_bar_comparison.pdfcooldown_0211_all.pdf
       Reply  Tue Feb 15 16:54:27 2022, rana, DailyProgress, Cryo vacuum chamber, Doubled Thermal Linkage Capacity run started 11 Feb 2022 
    Reply  Wed Feb 16 11:35:18 2022, Stephen, DailyProgress, Cryo vacuum chamber, Doubled Thermal Linkage Capacity run started 11 Feb 2022 
Message ID: 2720     Entry time: Tue Feb 15 11:59:22 2022     In reply to: 2717     Reply to this: 2721
Author: Radhika 
Type: DailyProgress 
Category: Cryo vacuum chamber 
Subject: Doubled Thermal Linkage Capacity run started 11 Feb 2022 

*Note: The RTD spring-clamped to the cold head gave spazzy readings for this cooldown, so the last cooldown's cold head temperature data was used instead for reference.

Looking at the data, there are some initial noteworthy observations:

The outer shield's conductive coupling to the copper bar / cold plate is much higher than previous cooldowns. Attachment 2 shows that the outer shield gets colder than the test mass, and around the 82 hr mark their temperatures cross.
We hoped to see a reduction by about a half in cooldown time for the 02/11 run, after effectively doubling the cross-sectional area of the copper bar. However, the data does not show x2 improvement, as seen in Attachment 1.

It could be that somehow the resistances of re-bolted joints increased significantly to compensate the lowered resistance of the bar, but this doesn't seem too likely. The more likely answer is the model overestimated the original resistance of the bulk of the copper bar relative to other components/joints in the chain. This means more work needs to be done, and hopefully a more realistic model will also resolve the discrepancy in early cooldown of the inner shield data. 

Attachment 2 shows the best fit for the new cooldown.

Attachment 1: Cu_bar_comparison.pdf  15 kB  | Hide | Hide all
Cu_bar_comparison.pdf
Attachment 2: cooldown_0211_all.pdf  28 kB  | Hide | Hide all
cooldown_0211_all.pdf
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