low temperature techniques course 2008
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Presentation given at the Institute of Physics Low Temperature Course 2008, sponsored by Cambridge Magnetic RefrigerationTRANSCRIPT
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Dr Kurt HaselwimmerCambridge Magnetic Refrigeration
Notes to a Low Temperature Physicist
or, what I wished I'd have known when I started
LT Techniques course, 26th Nov 2008
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Time
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PhD = 1000 days
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LT is difficult
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A Cabinet of Curiosities ?Ole Worm (1588-1654)
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Helium
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Another Curiosity ?
http://www.flickr.com/photos/noyespictures/2289512991
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Try Dry
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Pulse tubes now to 2.7K
Dryogenic – DMS-1000 system
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Wiring
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“God hangs the greatest weights upon the smallest wires”
Francis Bacon
http://www.flickr.com/photos/andrewmckaskill/16531297
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Don’t build if you can buy
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Rewiring a cryostat properly costs less than getting a powersocket installed. Do it right and do it only once.
http://www.cmr-direct.com
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Pumps andplumbing
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http://www.flickr.com/photos/arcanegazebo/445426559/
“A vacuum is a hell of a lot better than some of the stuff thatnature replaces it with”
Tennessee Williams
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• Always clean and grease o-rings• Only Use Viton O-rings – buna-N cracks
• Paint your KF-fittings
• Don't use poppet relief valves on vacuum cans
• Always boil-off flux on HS joints
• Buy SS flexibles from Kurt J Lesker
• Use plastic KF clamps from BOC edwards
• Use only bellows sealed valves on He-3
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Millikelvin work
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http://www.flickr.com/photos/arcanegazebo/3299089
The dilution fridge – the mainframe ofmK machines
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Keep it simple,stupid !
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http://www.flickr.com/photos/hynkle/2587828754
Simplicity means achieving themaximum effect with the minimummeans.
Koichi Kawana
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Entropy, S
Temperature
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Entropy, S
T MIN<50mK
B min = 0.1 T
B max = 6T
T BATH = 4.2K, 1.5K
Temperature
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Refrigerant
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Entropy, SB min = 0.1 T
B max = 6T
Temperature
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Refrigerant
SuperconductingMagnet
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Entropy, SB min = 0.1 T
B max = 6T
Temperature
1
T BATH = 4.2K, 1.5K
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Thermal Contact
Bath
RefrigerantPill
SuperconductingMagnet
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Entropy, SB min = 0.1 T
B max = 6T
Temperature
1
T BATH = 4.2K, 1.5K
2
T MIN<50mK
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Heat Switch
Bath
RefrigerantPill
SuperconductingMagnet
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Practical Refrigerators
Connection to Bath
Heatswitch
Sample Region (Double axis rotator)
Refrigerant
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LT is difficulta
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http://www.flickr.com/photos/rakkar/574407246
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Cambridge Magnetic Refrigeration
www.cmr.uk.com
Cryoconsumables - wiring, connectors etc
www.cmr-direct.com
Completely Dry systems -Dryogenic Ltd
www.dryogenic.com
Dr Kurt [email protected]