LOW TEMPERATURE CRYOCOOLERS

The regenerator is a key component of a regenerative cryocooler, and the performance of the refrigerator is almost entirely set by the performance of the regenerator. This proposal presents an innovative approach to the fabrication of regenerator structures using fine wires of a metal having high specific heat at low temperatures. Neodymium (Nd) spheres have been used in two-stage cryocoolers that can operate below 4K. If Nd mesh, having the proper structure and wire dimensions, can be fabricated, then much better performance can be expected. In a single-stage cryoccoler, the minimum temperature will be lowered below 20K, making the refrigerator very useful for devices using the new ceramic high temperature superconductors. The key feasibility demonstration in the Phase I effort will be the production in small quantities of copper jacketed Neodymium wire with diameters smaller than 0.002" (50x10(-6) meter).