JANIS CYROSTAT COOLING DOWN PROCEDURE

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JANIS CYROSTAT COOLING DOWN PROCEDURE
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Operation Procedures

• 1. Outside jacket of Dewar pump down
• 2. He reservoir pre-cooling
• 3. Liquid Nitrogen transfer
• 4. Liquid Helium transfer
• 5. Sample cooling

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Reference

• 1. Operating Instructions for the Janis Model SVT
  Research Cryostat, Operation Manual
• 2. Manual for the photoluminescence measurements
  in the 18-132A laboratory, UCLA
• 3. Cool-Down Procedure for 8-CNDT Optical
  Cryostat, 7-28-99, Greg Martinez

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Outside jacket of Dewar pump down

• 1. Make sure there is not water in He or LN2
  reservoirs
• 2. Evacuate the vacuum jacket.
• The recommended room temperature vacuum level is
  10-5 Torr1,(10-6Torr2), so a diffusion pump
  or a turbo pump is necessary.
• Based on Dr. Skromme Labs setup, a minimum
  vacuum level 1-2mTorr is required for a stable
  liquid Helium super-flow.
• Our case vacuumlt5 mTorr
• Baking over 50C is not allowed by manufacturer

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Outside jacket of Dewar pump down
To Sample tube
To Dewar jacket
To Pump
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Outside jacket of Dewar pump down
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He reservoir pre-cooling

• 1. Pump liquid He reservoir and backfill with
  Helium gas
• 2. Pump sample tube and backfill with Helium gas
• Make sure needle valve is not obstructed
• Close the needle valve loosely before the liquid
  nitrogen transfer
• 3. Unseal the He venting arm then transfer liquid
  nitrogen to He reservoir
• Step 1 is not very necessary, purging with gas
  Helium will be enough3 Close Dewar vacuum
  valve before liquid nitrogen transfer

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He reservoir pre-cooling
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He reservoir pre-cooling
He pumping arm
Liquid Nitrogen
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He reservoir pre-cooling

• 1. Open the liquid Helium valve 2 to 3 turns
  while filling the reservoir, make sure the valve
  does not freeze.
• 2. Turn off the LN2 switch and immediately begin
  to thaw the pumping arm with the heat gun before
  resealing it.

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He reservoir pre-cooling
Needle valve
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He reservoir pre-cooling
Thaw the pumping arm
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He reservoir pre-cooling
Seal the liquid Helium pumping arm Insert rubber
stoppers into the two/vent ports to prevent air
and moisture from entering the LHe reservoir
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Liquid Nitrogen Transfer
He gas adapter
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Liquid Nitrogen Transfer
Connect Helium gas to Helium fill/vent port
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Liquid Nitrogen Transfer
U tube
He siphon tube adaptor(with O-ring)
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Liquid Nitrogen Transfer
Nitrogen fill/vent port
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Liquid Nitrogen Transfer
Apply gas He to press liquid nitrogen to LN2
reservior
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Liquid Nitrogen Transfer
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Liquid Nitrogen Transfer
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Liquid Nitrogen Transfer
Rubber stopper
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Liquid Nitrogen Transfer
Fill liquid Nitrogen to LN2 reservoir
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Liquid Nitrogen Transfer
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Liquid Helium transfer
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Liquid Helium transfer
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Liquid Helium transfer
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Liquid Helium transfer
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Liquid Helium transfer
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Liquid Helium transfer
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Liquid Helium transfer
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Liquid Helium transfer
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Liquid Helium transfer
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Liquid Helium transfer
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Liquid Helium transfer
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Liquid Helium transfer
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Sample Cooling