A 20K Cooler for the Spaceport of Liquid Hydrogen

For the future spaceport and storage of liquid hydrogen NASA requires cryocoolers that can provide more than 10W of cooling at 20K. The closed-cycle cooling alternatives currently available for such applications are not well suited to their requirements. In many cases reliability is low and vibration high. In other cases coolers are too massive and inefficient. This proposal describes a two-stage pulse tube cooler (PTC) that combines a bootstrap staging configuration with an innovative second-stage regenerator design and a unique load-interface. The proposed cooler contains three innovative concepts that together will overcome the limitations of current cryocooler technologies: (1) the matrix for the second stage regenerator will be made from a newly-patented material having a heat capacity in excess of all other known materials, including lead (Pb), over a wide range of low temperatures (85K down to 15K), (2) the material for the second-stage regenerator will be formed into a novel matrix geometry, and (3) a unique load-interface will be an integral part of the cooler giving it the capability to cool distributed loads efficiently. The proposed pulse tube will be lightweight, efficient, reliable, vibration free, and easy to integrate into cryogenic dewars.