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Entry  Mon Jun 6 09:45:58 2022, Radhika, DailyProgress, Emissivity estimation, Megastat cooldown - repainted inner shield aquadag, added aquadag foil to cold plate 6x
    Reply  Wed Jun 8 12:15:06 2022, Radhika, DailyProgress, Emissivity estimation, Megastat cooldown - repainted inner shield aquadag, added aquadag foil to cold plate 
       Reply  Thu Jun 9 10:42:26 2022, Radhika, DailyProgress, Emissivity estimation, Megastat cooldown - repainted inner shield aquadag, added aquadag foil to cold plate MS_cooldown_2022-06-02_data.pdf
          Reply  Fri Jun 10 09:47:07 2022, Radhika, DailyProgress, Emissivity estimation, Megastat cooldown - repainted inner shield aquadag, added aquadag foil to cold plate hmfile_hash_88f68a98.png
             Reply  Fri Jun 10 16:23:04 2022, rana, DailyProgress, Emissivity estimation, Megastat cooldown - repainted inner shield aquadag, added aquadag foil to cold plate 
Message ID: 2783     Entry time: Thu Jun 9 10:42:26 2022     In reply to: 2781     Reply to this: 2784
Author: Radhika 
Type: DailyProgress 
Category: Emissivity estimation 
Subject: Megastat cooldown - repainted inner shield aquadag, added aquadag foil to cold plate 

I encountered several puzzles in the data from this cooldown (Attachment 1):

1. Due to residual challenges with getting the Megastat SLOW channels recorded to frames (after flood), we've been using a USB to extract data form the CTC100. However, only ~48 hours of cooldown were recorded on the drive - we lost data from the rest of the cooldown. I'm hoping this is due to storage limits on the USB, and if so I will decrease the sampling rate of the CTC100 and/or source a USB with larger storage. Of course this is a temporary solution, and efforts would be better spent on getting data recorded in frames. For now, since every component had reached steady state (except the test mass), most parameters can theoretically still be inferred from the data we obtained. (Note that data logging started a bit after the cryocooler was switched on.)

2. The inner shield appears to have reached a steady-state temperature lower than that of the cold head. This is bizzare, and non-physical - the cold head should be the component supplying cooling power to the rest of the system. Our current Megastat model would not predict such behavior under any choice of parameters. I replaced the inner shield RTD before this cooldown, so I am hoping the new RTD has a different calibration curve than what the CTC100 was expecting. If this is the case, I should be able to use the data to undo the existing calibration and obtain correctly-calibrated temperature for the inner shield. It is worth noting that the new RTD accurately measured room temperature, so if this theory is correct then the calibration error only exists at low temperatures.

Attachment 1: MS_cooldown_2022-06-02_data.pdf  118 kB  Uploaded Thu Jun 9 12:32:47 2022  | Hide | Hide all
MS_cooldown_2022-06-02_data.pdf
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