Continuous cooling from 10 to 4 K using a toroidal ADR

Michael DiPirro, Edgar Canavan, Peter Shirron, and James Tuttle

NASA/Goddard Space Flight Center
Cryogenics and Fluids Branch
Code 552
NASA/ Goddard Space Flight Center
Greenbelt, MD 20771

Future large infrared space telescopes will require cooling to 4 K to achieve background limited performance for submillimeter wavelengths. These observatories will require lifetimes of many years and will have relatively large cooling requirements making stored helium dewars impractical. We have designed and are building an adiabatic demagnetization refrigerator (ADR) for use in cooling relatively large loads (10 to 100 mW) at 4 K and rejecting that heat to a cryocooler operating at 10 K. The ADR magnet consists of eight short coils wired in series and arranged in a toroid to provide self shielding of its magnetic field. We will use gas gap heat switches to alternately connect the toroid to the cold load and the warm heat sink. A small continuous stage will maintain the cold end at 4 K while the main toroid is recycled.

Pages 559-564
Cryogenics, Volume 44, Issues 6-8 (June - August 2004)
[2003 Space Cryogenics Workshop, Edited by M. Larson and W. A. Holmes]