Research of Combined Use of Magnetic Refrigeration Technology With a Refrigerant Circulation System for Cooling a High Temperature Superconducting Coil

A refrigerant circulation cooling system for a HTS (High Temperature Superconducting) coil shows better cooling performance than a heat conduction cooling system when the distance between the cryocooler and the HTS coil becomes large because the temperature gradient between the cryocooler and the HTS coil becomes small. This study proposes to combine MR (Magnetic Refrigeration) technology with this cooling system. MR requires a magnetic field change applied to a MCM (Magnetocaloric Material). A method of causing the magnetic field change by inserting or removing magnetic shields made of superconductors is considered in the present study. One dimensional heat transfer analysis showed that the larger a magnetic field change, the better cooling performance of the MR combined cooling system, and the more robust cooling assistance can be obtained without depending on heat load to the HTS coil. Numerical analysis based on the experiment evaluating the magnetic shielding performance of a pair of superconductors revealed the temperature and dimensional dependence of the magnetic shields.