A refrigerator having a plurality of cooling stages

摘要

In a refrigerator for cooling a superconducting coil (305) and having a plurality of cooling stages each of which includes a regenerator, at least the final stage (314) includes a pulse tube refrigerator. The axis of the pulse tube (337) is substantially parallel to the axis of the pulse tube regenerator (332). The intersection angle between the axis of the pulse tube and the axis of at least the first of the cooling stages (313) is set at a predetermined value, preferably one of 90 or 180 degrees. The regenerator (332) preferably includes a magnetic coldness-accumulating material (334). The pulse tube is situated such that the low-temperature portion (A) of the pulse tube is located downward in the direction of gravity as compared to the high-temperature portion (B).