Development of powerful magnetic regenerator materials and verification of their effectiveness

Abstract We have succeeded in obtaining a refrigeration power of more than 1.1 watts. at 4.2 K using a GM(Gifford-McMahon) refrigerator. The most important improvement made in our machine was application of a multi-layered type magnetic regenerator which was composed of several kinds of heavy rare earth magnetic materials with low critical temperature in the range from 15 K to 4 K. We first describe the concept of this regenerator and then showsome experimental results which verify its superiority.