LN2-Precooled Two Stage Pulse Tube Cooler

One of the fundamental implementation challenges for 4K cryocoolers to support superconducting electronics (SCE) is the size of the cooler. For platforms on which there is the possibility of using a"thermal battery,"i.e., a reservoir of cryogenically-cooled fluid that can be used to precool the cryogenic subsystem, there is a tremendous opportunity to reduce the required size of the cryocooler dramatically. For example, the upper stage(s) of expander components can be replaced with a simple two-fluid heat exchanger, reducing expander volume and, more substantially, compressor volume by reducing the required exergy lift. Success on this program is thus expected to lead to insertion opportunities on a wide range of packaging-constrained platforms that would otherwise preclude closed-cycle refrigeration, and in so doing enable the use of high performance SCE-based RF communications electronics on platforms that are presently the exclusive purview of traditional approaches.