used by the compressor 2 in a preferred embodiment the constituents of the gas mixture include r116 c 2 f 6 the high pressure primary gas mixture then passes through a primary heat exchanger 24 i e a recuperator heat exchanger specifically through a high pressure passageway of the primary heat exchanger 24 where it is still further cooled to a lower temperature of approximately minus 80 degrees celsius the gas mixture then flows to the primary jt expansion element 26 after isenthalpic expansion in the primary expansion element 26 the expanded low pressure gas mixture cools target tissue 30 because the oil which reaches the primary expansion element 26 is already in a very dilute solution with condensed refrigerants the likelihood of the expansion element 26 becoming blocked is reduced significantly then the low pressure primary gas mixture passes back through a low pressure passageway in the primary heat exchanger 24 the low pressure gas mixture then returns to an inlet of the primary compressor 2 the secondary loop 8 includes a high pressure path and a low pressure path the secondary loop compressor 4 compresses the secondary refrigerant to a pressure of approximately 300 psia according to one embodiment the secondary refrigerant is r410a the high pressure secondary refrigerant then flows from an outlet of the secondary compressor 4 through a condenser 14 the condenser 14 changes the secondary refrigerant from a superheated vapor to a sub cooled liquid the high pressure secondary refrigerant then flows from the outlet of the condenser through the flexline 18 the high pressure.