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Entry  Fri Sep 24 13:12:00 2021, Radhika, General, Heat Load, Mariner cooldown model status + next steps 
    Reply  Mon Sep 27 17:01:53 2021, rana, General, Heat Load, Mariner cooldown model status + next steps 
       Reply  Wed Sep 29 16:15:19 2021, Radhika, General, Heat Load, Mariner cooldown model status + next steps Heat_Load_Sketch_geometry.pdfHeat_Load_Sketch_diagram.pdfheating_cooling_P_vs_T.pdfCooldownTM_radiative.pdf
          Reply  Tue Oct 5 17:46:14 2021, Radhika, General, Heat Load, Mariner cooldown model status + next steps Heat_Load_Sketch_all.pdfVaryingISA.pdfCooldownTM.pdf
             Reply  Fri Oct 15 13:45:55 2021, Radhika, General, Heat Load, Mariner cooldown model status + next steps VaryingTMl.pdf
                Reply  Fri Oct 15 14:31:15 2021, Radhika, General, Heat Load, Mariner cooldown model status + next steps VaryingISA.pdfVaryingTMl.pdf
Message ID: 32     Entry time: Wed Sep 29 16:15:19 2021     In reply to: 31     Reply to this: 37
Author: Radhika 
Type: General 
Category: Heat Load 
Subject: Mariner cooldown model status + next steps 

Attachment 1 is a geometric diagram that reflects the current state of the ITM cooldown model, introduced in [30]. The inner shield is assumed to be held at 77K for simplicity, and 2 heat sources are considered: laser heating, and radiative heating from the room-temperature snout opening. The view factor Fij between the snout opening and test mass (modeled as 2 coaxial parallel discs separated by length L - equation found in Cengel Heat Transfer) is calculated to be 0.022. The parameters used in the model are noted in the figure.

Attachment 2 is a simplified diagram that includes the heating/cooling links to the test mass. At 123K, the radiative cooling power from the inner shield (at 77K) is 161 mW. The radiative heating from the snout opening is 35 mW, and the laser heating (constant) is 101.5 mW. Due to the tiny view factor betwen the snout opening and the test mass, most of the heat emitted by the opening does not get absorbed. 

The magnitudes of heating and cooling power can be seen in Attachment 3. Lastly, Attachment 4 plots the final cooldown curve given this model. 

My next step is to add the outer shield and fix its temperature, and then determine the optimal size/location of the inner shield to maximize cooling of the test mass. This is question was posed by Koji in order to inform inner shield/outer shield geometric specs. Then, I will add a cold finger and cryo cooler (conductive cooling). Diagrams will be updated/posted accordingly.

Attachment 1: Heat_Load_Sketch_geometry.pdf  21 kB  Uploaded Wed Sep 29 17:15:36 2021  | Hide | Hide all
Heat_Load_Sketch_geometry.pdf
Attachment 2: Heat_Load_Sketch_diagram.pdf  15 kB  Uploaded Wed Sep 29 17:15:49 2021  | Hide | Hide all
Heat_Load_Sketch_diagram.pdf
Attachment 3: heating_cooling_P_vs_T.pdf  13 kB  Uploaded Wed Sep 29 17:16:07 2021  | Hide | Hide all
heating_cooling_P_vs_T.pdf
Attachment 4: CooldownTM_radiative.pdf  14 kB  Uploaded Wed Sep 29 17:16:41 2021  | Hide | Hide all
CooldownTM_radiative.pdf
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