DEVELOPMENT OF A PRACTICAL PULSE TUBE REFRIGERATOR: CO-AXIAL DESIGNS AND THE INFLUENCE OF VISCOSITY.

PULSE TUBE REFRIGERATION OFFERS THE POTENTIAL TO DEVELOP AN INHERENTLY RELIABLE CRYOCOOLER. REFRIGERATION RESULTS FROM A PROCESS KNOWN AS SURFACE HEAT PUMPING INVOLVING THE THERMAL INTERACTION BETWEEN A PULSATING GAS COLUMN AND ADJACENT TUBE WALL. A COMPACT CO-AXIAL DESIGN WHICH MAY BE READILY MINIATURIZED IS DESCRIBED IN DETAIL AND REFERENCE IS MADE TO A VALVED (OR ORIFICE) DESIGN WHICH OFFERS HIGHER PERFORMANCE. DEVELOPMENT OF SUCH A TUBE REQUIRES AN UNDERSTANDING OF THE INFLUENCE OF VISCOSITY ON SURFACE HEAT PUMPING. IT IS CONCLUDED THAT A TRULY PRACTICAL PULSE TUBE OFFERING A WORKING TEMPERATURE OF 70 K SHOULD BE POSSIBLE IF THE CO-AXIAL AND VALVED DESIGNS ARE COMBINED IN A SINGLE DEVICE.