low temperature techniques course 2008
DESCRIPTION
Presentation given at the Institute of Physics Low Temperature Course 2008, sponsored by Cambridge Magnetic RefrigerationTRANSCRIPT
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
Time
PhD = 1000 days
LT is difficult
A Cabinet of Curiosities ?Ole Worm (1588-1654)
Helium
Another Curiosity ?
http://www.flickr.com/photos/noyespictures/2289512991
Try Dry
Pulse tubes now to 2.7K
Dryogenic – DMS-1000 system
Wiring
“God hangs the greatest weights upon the smallest wires”
Francis Bacon
http://www.flickr.com/photos/andrewmckaskill/16531297
Don’t build if you can buy
Rewiring a cryostat properly costs less than getting a powersocket installed. Do it right and do it only once.
http://www.cmr-direct.com
Pumps andplumbing
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
• 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
Millikelvin work
http://www.flickr.com/photos/arcanegazebo/3299089
The dilution fridge – the mainframe ofmK machines
Keep it simple,stupid !
http://www.flickr.com/photos/hynkle/2587828754
Simplicity means achieving themaximum effect with the minimummeans.
Koichi Kawana
Entropy, S
Temperature
Entropy, S
T MIN<50mK
B min = 0.1 T
B max = 6T
T BATH = 4.2K, 1.5K
Temperature
Refrigerant
Entropy, SB min = 0.1 T
B max = 6T
Temperature
Refrigerant
SuperconductingMagnet
Entropy, SB min = 0.1 T
B max = 6T
Temperature
1
T BATH = 4.2K, 1.5K
Thermal Contact
Bath
RefrigerantPill
SuperconductingMagnet
Entropy, SB min = 0.1 T
B max = 6T
Temperature
1
T BATH = 4.2K, 1.5K
2
T MIN<50mK
Heat Switch
Bath
RefrigerantPill
SuperconductingMagnet
Practical Refrigerators
Connection to Bath
Heatswitch
Sample Region (Double axis rotator)
Refrigerant
LT is difficulta
http://www.flickr.com/photos/rakkar/574407246
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]