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DMRadio 50L Cold Snout

DMRadio Collaboration Meeting

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August 5th, 2024

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Outline

  1. Setup & Goals
  2. Cooldown 1
  3. Cooldown 2
  4. Cooldown 3
  5. Future & Schedule

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Setup - Woodstock Configuration

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Snoopy

Woodstock

Cold Snout

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Setup - Snoopy Configuration

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Testing vacuum nipple

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Expected Thermal Gradients

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20mK

MXC

Cold Finger

20 mK

30 mK

Vespel Screws

Vespel Screws

Braid

Still

841 mK

Braid

Rod

Tube

Puck

884 mK

1 K

Total heat load:

(see Tori’s talk)

Total heat load:

13 uW

414 uW

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Cooldown 1

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MXC plate

Adapter plate heater (varnished to Cu adapter plate)

Vbar heater (varnished)

Cold finger heater (varnished)

Shmount heater and RuOx thermometer (screwed on)

Braid

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Vespel (~2 μW on base stage)

Vespel (~2 μW on base stage)

4 K shield

40 K shield

1 K cold finger

4 K shield cap radiation (~0.01 μW on base stage)

Three open M4 screw holes on 40 K shield (~3000 μW on base stage)

Three open M4 screw holes on 4 K shield

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Cooldown 1 Results

Still Temperature: 880 mK

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MXC Temperature: 32.9 mK

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20mK Shmount Temperature: 393 mK

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Cooldown 1 - 20 mK Interfaces

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Shmount heater

20 mK CF heater

Vbar heater

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Adapter plate heater

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MXC heater

1 K thermometer

20 mK thermometer

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Cooldown 2

Improvements

Cover holes in 4K and 40K shields

Improve 20mK shmount to make assembly easier

Add 1K shmount

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20mK shmount

1K shmount

Covered holes in 40K and 4K shields

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Cooldown 2 - Heaters & Thermometers

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20 mK

1 K

20mK Cold Finger

20mK Shmount

Adapter Plate

Vbar

1 K Rod

1 K Tube

Thermometers

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Cooldown 2 - Insulating Connections

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Puck

1 K → 4 K

Vespel Screws

20mK → 1 K

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Cooldown 2 Results - Temperatures

Still Temperature: 884 mK

MXC Temperature: 17.65 mK

20mK Shmount Temperature: 176 mK

1K Shmount Temperature: 914 mK

Still Temperature: 880 mK

MXC Temperature: 32.9 mK

20mK Shmount Temperature: 393 mK

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Cooldown 2

Cooldown 1

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Cooldown 2 Results - 1 K Interfaces

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Rod heater

Tube heater

Still heater

Takeaway: Still-to-Rod interface is weakest

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Cooldown 2 Results - 20mK Interfaces

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Shmount heater

20 mK CF heater

Vbar heater

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Adapter plate heater

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MXC heater

1 K thermometer

20 mK thermometer

Takeaway: Adapter Plate-to-Vbar interface is weakest

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Cooldown 2 - Vespel Screws

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Expected: 4 uW/K

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Measured: 3 uW/K

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Cooldown 2 - Heat Loads

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20mK path

1K path

Heat Load: 4 uW

Heat Load: 10 uW

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Cooldown 3

Improvements

1K thermal straps (increase number and improve contact area)

Vbar-to-braid fit (new vbar with better fit)

Al tape over seams

4K thermometer on the end of the shield

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Better 1 K straps

Vbar-to-braid clamp

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Cooldown 3 Results

Still Temperature: 884 mK

MXC Temperature: 17.65 mK

20mK Shmount Temperature: 176 mK

1K Shmount Temperature: 914 mK

Still Temperature: 880 mK

MXC Temperature: 32.9 mK

20mK Shmount Temperature: 393 mK

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Still Temperature: 911 mK

MXC Temperature: 17.62mK

20mK Shmount Temperature: 81 mK

1K Shmount Temperature: 1 K

4K Shield Temperature: 4.2 K

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Cooldown 2

Cooldown 1

Cooldown 3

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Cooldown 3 Results

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Live Monitoring

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Next Steps

  • Weld 20mK braid to cold finger
  • Gold plate interfaces
  • Manufacture 4K and 40K flexible connections

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Schedule & Goals

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August

September

October

November

4K flexible connection

(Princeton)

40K flexible connection

Cooldown 3

Cooldown 4

Cooldown 5

Bellows adapter plate

Goal thermal gradient