Performance of the fast-ramping high temperature superconducting magnet system for an active magnetic regenerator

Abstract

Fast magnetic field alternation is indispensable for continuously magnetic refrigeration. An active magnetic regenerative refrigerator (AMRR), a type of the magnetic refrigerator, utilizes magnetocaloric effect (MCE) of magnetic refrigerants which occurs during magnetization and demagnetization processes. A conduction cooled high temperature superconducting (HTS) magnet can be one of the prospective candidates as an alternating magnetic field generator. The cryogen-free HTS magnet for the AMRR has been developed for fast ramping and described in this paper. The magnet consists of twelve double pancake GdBCO coils which are insulated with polyimide tape. A two-stage GM cryocooler is employed to cool down the magnet. In order to remove heat produced by AC loss with small temperature difference, thermal links between the cryocooler and the magnet are carefully designed. 6 kW DC power supply is used to energize the HTS magnet and discharged by an external dump resistor.