Thermoacoustic refrigerator for space applications

Long‐lived, space‐based cryocoolers with low vibration levels are necessary in a variety of applications, including the cooling of infrared sensors and high Tc superconductors. A thermoacoustic refrigerator designed to function autonomously in a Space Shuttle Get Away Special (GAS) canister will be described that has no sliding seals and oldy 15 gm of reciprocating mass. It is capable of cooling to 100 K below room temperature with a single stage “stack” consisting of rolled plastic film and short lengths of 10‐lb test monofilament fishing line as the spacers. This presentation will concentrate on the modifications to the basic refrigerator design (U.S. Patent No. 4,722,201, issued 2 Feb. 1988) that improve both its electroacoustic and thermoacoustic efficiencies. These improvements include the use of a helium‐xenon gas mixture as the thermodynamic working fluid and a neodymium‐iron‐boron electrodynamic driver with a titanium suspension. Custom electronic circuits necessary to control the refrigerator (microprocessor, bubble memory data recorder, phase‐locked loops, automatic gain controls, amplifiers, multiplexed diode thermometers, etc.) and special fabrication techniques necessary to confine the helium for years while permitting electrical feed through will also be disclosed. [Work supported by the Office of Naval Research, Office of Naval Technology, and the Naval Postgraduate School Research Foundation.]