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.