Some examples of powerful Refrigerators
ULT set-ups cooling 3He well below 100 µK
Estimated lowest temperatures are on the order of 85 µK (actual temperatures may be even lower, the thermometers loosing sensitivity).
An Advanced Dilution Refrigerator Designed for the New Lancaster Microkelvin Facility
, D. J. Cousins, S. N. Fisher, A. M. Guenault, R. P. Haley, I. E. Miller, G. R. Pickett, G. N. Plenderleith, P. Skyba, P. Y. A. Thibault, and M. G. Ward, J. of Low Temp. Phys. 114, 547 (1999) (This machine holds the present record of low temperatures with a dilution refrigerator (1.75 mK))
DN1: The new Grenoble 100 microKelvin refrigerator
, C. Bäuerle, Y. Bunkov, S.N. Fisher, Chr. Gianese and H. Godfrin, Czekoslovak J. of Phys. 46, suppl S5, 2791-2792, 1996. This ULT machine, designed in the early 90's (H. Godfrin and C. Gianèse) for NMR on 2D-3He samples, is particularly long: the demagnetization coil being far from the NMR coil, the NMR field is very homogeneous. A Lancaster stage (G.R. Pickett and S.N. Fisher) was installed first, and used in “Cosmology experiments
” (Kibble-Zurek effect), and particle detectors projects (MacHe3
and ULTIMA projects
). The Lancaster stage was replaced later on by a laminar copper stage (Y. Bunkov) for 3He/aerogel and 2D-3He studies.
T<5 mK Refrigerator for Neutron scattering
In this type of refrigerators the helium bath does not surround the lower part of the cryostat. Radiation shields enclose the lower section. The refrigerator shown here (named “DRILL”) was developed by CNRS and ILL in Grenoble (H. Godfrin, C. Gianèse and R. Chung ). It also has a LN2 bath for long operation time between helium transfers.