Structure design of electromagnetic shield on reactor applied for switch network unit of EAST poloidal field

Large magnetic field generated by reactor applied for the switch network unit of Experimental Advanced Superconducting Tokamak (EAST) poloidal field can seriously disrupt the proper operation of discharge circuit. This paper presents a detailed analysis of the reactor burnout accident during its operation, and to solve the problem, three different types of shielding structure are proposed and shielding performances are compared. And in order to obtain the best shielding performance, an optimal structure is investigated by finite element method (FEM) taking into account eddy current.