Miniature J-T refrigators using adsorption compressors

Abstract

More sophisticated cooling systems for the employed detectors will be needed to satisfy the demand for higher resolution and sensitivity of various detectors used in space missions. The design of the cooling system must take into consideration the unique environment of space vehicles. It is pointed out that a deep space vehicle usually has an ample supply of waste heat from a radioisotope thermoelectric generator (RTG) and has a heat sink near zero Kelvin. Passive radiative coolers have been used for cooling temperatures above 90 K. Cooling below 90 K is currently handled by phase changes of solid or liquid cryogens or mechanical refrigeration. However, the weight of the cryogen may be a problem in a long duration space mission. Refrigerators of small cooling capacity are required in many spacecraft applications. For some future NASA missions, a multistage Joule-Thomson refrigerator using adsorption compressors appears particularly attractive. A study is discussed of four different refrigeration stages which use charcoal as the adsorbent. The adsorbed gases are nitrogen, helium, hydrogen, and neon.