Notes to a Low Temperature Physicist
or, what I wished I'd have known when I started
LT Techniques course, 26th Nov 2008
Dr Kurt Haselwimmer
Cambridge Magnetic Refrigeration

Time

PhD = 1000 days

LT is difficult

A Cabinet of Curiosities ?
Ole Worm (1588-1654)

Helium

Another Curiosity ?
http://www.flickr.com/photos/noyespictures/228951299

Try Dry

Pulse tubes now to 2.7K
Dryogenic – DMS-1000 system

Wiring

http://www.flickr.com/photos/andrewmckaskill/16531297
“God hangs the greatest weights upon the smallest wires”
Francis Bacon

Don’t build
if you can buy

http://www.cmr-direct.com
Rewiring a cryostat properly costs less than getting a power
socket installed. Do it right and do it only once.

Pumps and
plumbing

http://www.flickr.com/photos/arcanegazebo/445426559
/
“A vacuum is a hell of a lot better than some of the stuff that
nature 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 of
mK machines

Keep it simple,
stupid !

Simplicity means achieving the
maximum effect with the minimum
means.
Koichi Kawana
http://www.flickr.com/photos/hynkle/2587828754

Entropy, S
Temperature

Entropy, S
B min = 0.1 T
B max = 6T
Temperature
T MIN <50mK T BATH = 4.2K, 1.5K

Refrigerant

Entropy, S
B min = 0.1 T
B max = 6T
Temperature

Superconducting
Magnet
Refrigerant

Entropy, S
B min = 0.1 T
1 B max = 6T
Temperature
T BATH = 4.2K, 1.5K

Bath
Thermal Contact
Superconducting
Magnet
Refrigerant
Pill

Entropy, S
B min = 0.1 T
1 B max = 6T
2
Temperature
T MIN <50mK T BATH = 4.2K, 1.5K

Bath
Heat Switch
Superconducting
Magnet
Refrigerant
Pill

Connection to Bath
Heatswitch
Sample Region (Double axis rotator)
Refrigerant
Practical Refrigerators

a
LT is difficult

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 Haselwimmer
Kurt@cmr.uk.com