Advanced Verification and Validation techniques

We propose an affordable, compact, reliable, lightweight, andeffi-cient 4K refrigerator for superconducting electronicsapplications. The Phase I Program showed that such arefrigerator is possible, building on advances in refrigeratormaterials technology. The Phase I Program culminated in theconceptual design of a 4K refrigerator based on a new andinnovative expander and a conventional compressor repackaged tomeet the space and power limitations of military and commercialapplications. The Phase II Base effort will complete thedetailed design of the expander and compressor and will fabricateand test the expander using a commercial compressor. The PhaseII Option 1 effort will fabricate the compressor and integratethe compressor and expander to form a prototype 4K refrigeratorfor superconducting applications. Option 2 will integrate the 4Krefrigerator with super-conducting electronics to produce anintegrated demonstration of a se-lected application ofsuperconducting electronics (e.g. voltage stan-dard or analog-to-digital converter). The integrated demonstration is theprototype for a product that will establish a commercial base forthe 4K refrigerator, ensuring that it will be available andaffordable for other military and commercial superconductingelectronic applica-tions. In Phase III, we will continuedevelopment of new applications partnering with selectedsuperconducting electronics companies.