Cryocables à cycle Stirling de très faible puissance utilisant des matériaux plastiques et composites.

An experimental investigation of several concepts for very-low-power cryocoolers for operating highly-sensitive superconducting
devices has been undertaken. The devices to be cooled are those using Josephson junctions, such as SQUID magnetometers, voltage standards and A/D converters. The common basic feature of the concepts is that very low levels of magnetic, electric, and mechanical interference are potentially realizable. Nylon and epoxy-glass composites have been used for cold cylinders, pistons, and displacers. A multi-stage Stirling machine of these materials reliably maintains a temperature below 10 K, with a few mW heat load and an input drive power of 50 W. A single-stage machine maintains a temperature in the neighbourhood of 4 K with the hot end at 10 K and a drive power of the order of 5 W. Specific heats and thermal conductivities of the materials have been measured between 5 and 10 K, for purposes of analysis of regeneration inefficiency.