ANALYSIS AND CALCULATION OF AXIAL HEAT CONDUCTION LOSSES OF HIGH FREQUENCY MINIATURE CO-AXIAL NONMETALLIC PULSE TUBE CRYOCOOLERS

The axial heat conduction losses through the high frequency miniature co-axial nonmetallic pulse tube cryocoolers（PTCs）was analyzed and calculated.It compares with those through conventional metallic PTCs.The usage of nonmetallic materials with low heat conductivity is beneficial to a better performance provided that only the axial heat conduction losses are considered.For each of the two sample PTCs,the axial heat conduction loss through the gas in each tube exceeds that through the tube wall and thus becomes the biggest one,while that through regenerator matrix becomes neglectable.The characteristics mentioned above are remarkably different from those of conventional metallic PTCs with the same geometrical dimensions.