A HIGH-CAPACITY 0.23 K HE-3 REFRIGERATOR FOR BALLOON-BORNE PAYLOADS

We describe the design, operation, and performance of a high capacity, single stage, He-3 refrigerator optimized for balloon-borne payloads. A temperature of similar to 0.2 K is routinely maintained for more th an seven days at similar to 100 mu W total heat load. Recycling can be completed in less than 12 h. A simple design avoids valves and explic it heat switches, resulting in simplified construction and improved pe rformance. A numerical model characterizes the operating temperature o f the system over a large range of conditions. (C) 1996 American Insti tute of Physics.