CARNOT MAGNETIC REFRIGERATOR OPERATING BETWEEN 1.4-K AND 10-K

A magnetic refrigerator operating directly from 10 to 1.4 K has been constructed and tested. The refrigerator is a static system which operates following the Carnot cycle using a pulsed magnet and thermal switches. Typical experimental results were 550 mW at 4.5 K using a Dy3Al5O12 refrigerant and 100 mW at 1.8 K using Gd3Ga5O12. Without a cooling load, the lowest temperature obtainable was 1.36 K. The Carnot efficiencies were 30% at 2.0 K and 38% at 4.4 K. A cooling test for a superconducting magnet was also performed.