Fast Discharging Behavior of High Temperature Superconducting Coils With Copper Rings and Plates

Fast energy extraction using dump resistances is an effective method for quench protection of high temperature superconducting (HTS) magnets. Copper frames are often applied in HTS magnets for conduction cooling and mechanical support. Previous studies have shown that copper plates can accelerate the energy release of HTS coils during discharging operations with dump resistance, which is favorable for fast quench protection. Copper rings distributed at the inner and outer diameters of HTS coils can provide a strong mechanical support for the possible electromagnetic strain in high magnetic fields. This paper studies the effect of copper rings and plates on fast discharging process of an insulated HTS double pancake coil by finite element method. An optimized structure composed of copper rings and plates is proposed, and its effect on fast discharge is analyzed. The results show that copper plates show better performance than copper rings in accelerating energy release and reducing hot spot temperature of the coil. During discharging process, the optimized structure can absorb considerable energy from the HTS coil and significantly reduce the hot spot temperature. The optimized structure is a promising alternative for fast quench protection of HTS magnets.