Experiments on the Production of Very Low Temperatures by Two-Stage Demagnetization

Abstract

A two-stage demagnetization apparatus employing a superconducting wire as the thermal switch between the stages is described. Temperatures in the region of 0.003° K. have been obtained using a magnetic field of only 4,200 gauss. The problem of thermal insulation was investigated and the residual heat inflow after demagnetization was reduced to one erg/min. The possibility of employing a superconducting switch in cyclical magnetic cooling systems and in nuclear demagnetization is discussed.