Displacement-Type He II Heat Switch

Abstract
The operation of a heat switch is described in which the conducting substance is liquid He II and in which the nonconducting state is achieved by displacing the He II with a poor conductor, e.g., Teflon. The switch is well suited for use in the first stage of a magnetic refrigerator operating with a bath temperature near 1°K. At this temperature it performs better than a lead superconducting switch.