| 摘要 |
PROBLEM TO BE SOLVED: To provide a cryogenic refrigerator that is improved in refrigeration performance with reduced heat loss.SOLUTION: A cryogenic refrigerator includes: a cylinder 12; a displacer 14 accommodated movably forward and backward in the cylinder 12; a gap 40 which is formed between the inner periphery surface of the cylinder 12 with a diameter of &phgr;and the outer periphery surface of the displacer 14 with a diameter of &phgr;, and through which a refrigerant gas flows; and a depressed part 38 formed on the outer periphery of the displacer 14 or the inner periphery of the cylinder 12. The ratio of the volume, V, of the depressed part 38 to the volume, V, of the gap 40 satisfies a condition of 8≤V/V≤75. |
