ABSTRACT
Cryogenic heat switches (CHSs) are novel instruments with controlled variable heat conduction, working in a certain temperature region about from 50 mK up to 400 K. Heat switches can alternatively provide high thermal connection or ideal thermal isolation to the cold mass. These cryogenic heat switches are widely applied in a variety of unique cryogenic devices and critical space applications. Based on their working principles, cryogenic heat switches can be characterized into solid heat switches (SHSs) and gas heat switches (GHSs). These solid heat switches relying on the superconducting-normal phase change, magnetic levitation suspension, shape memory alloys, differential thermal expansion, and piezoelectric effect are discussed. Switches based on gas properties, helium or hydrogen gap-gap heat switches, cryogenic diode heat switches, and heat pipe heat switches are also introduced in detail. Finally, comparisons of advantages and limitations of the different cryogenic heat switches are briefly summarized, with an outlook for future thermal management solutions.
