NSF Award
8722128
The object of this Phase II program is to fabricate and test novel cryogenic composites designed for use as regenerators in closed-cycle cryocoolers operating below 10 K. The material is a composite of helium self-loaded into a metallic extended surface structure whose dispersion form is suitable for the thermal flux and frequency requirements of regenerators. High effective heat capacity from 3 - 6 K derives from the latent heat of vaporization and condensation of subcritical helium, and high heat capacity below 10 K derives from the sensible heat capacity of pressurized helium. High, anisotropic thermal conductivity in the regenerator derives from the geometric form of the metallic component. The combination of high heat capacity and high radial thermal conductivity allows for rapid thermal penetration and high regenerator effectiveness. The potential exists to achieve significant refrigeration power at liquid helium temperatures with a closed-cycle cryocooler not involving a Joule-Thomson gas- Throttling stage.
