4.0 K cryocooler project

The regenerative, shuttle, conduction, and viscous losses to be expected in a nonmagnetic cryocooler were calculated. Materials suitable for use in the low temperature parts of the cooler were identified and tested. A preliminary system for a cryocooler test station and an advanced system for the advanced prototypes cryocooler were designed. A thermal isolation apparatus, or dewar, was designed and fabricated. A single stage Stirling cylinder in a cryocooler configuration was designed, constructed, and tested. It was found that adding He-3 as the working fluid to one configuration improves performance. The problem of building the static He-4 regenerator is addressed. A Malone style stage was designed, constructed, and tested. The magnetic and vibrational signature of the operating cryocooler was measured with an external magnetometer and gradiometer. System reliability is summarized.