A throttle cycle refrigerator operating below 77 K

A cryocooler has been developed that uses a unique refrigerant in a throttle cycle to achieve temperatures below the normal boiling point of liquid nitrogen. 70 K was achieved at no load condition and continuous operation with a 1.5 W heat load below 77 K has been demonstrated. The refrigerator consists of a compressor package that is similar to a standard air conditioning system, a cold end which has no moving parts that consists of a heat exchanger with a cold plate, and two gas lines connecting the compressor and the cold end. The system requires no maintenance. Several prototypes have been built, tested and delivered to a customer for application in the field of high temperature superconducting filters for cellular phone communications. The cold end has the design flexibility to be customized for different applications. System performance can also be customized by designing different refrigerants that can be used without the need to modify the hardware