Mechanically operated thermal switches for use at ultralow temperatures

Abstract

Some thermal switch designs are discussed in which a ⁴He actuated bellows is used to make or break mechanical contact between two sections containing metallic surfaces. Techniques are discussed which permit the switch sections to make thermal contact to liquid ³He by employing a large liquid−solid surface area. Designs are presented for a Pomeranchuk cell and an adiabatic demagnetization cell, which incorporate the bellows−actuated mechanical switch concept.