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Description
The BEST (Burning Plasma Experimental Superconducting Tokamak) is a compact tokamak device under design. The parameters of the device include major radius is 3.6m, minor radius is 1.1m, plasma current is 7MA, and central field strength is 6.15T. The magnet system of the device consists of 12 central solenoid coils (6 high-temperature superconducting coils and 6 low-temperature superconducting coils), 16 TF coils, and 7 PF coils. The PF coils mainly contribute to the shaping and equilibrium of plasma. The design of BEST PF coils is based on three operating mode (steady state operation mode, hybrid operation mode and induction operation mode). Based on the magnetic field distribution of each PF coil, the superconducting material of PF coil is determined, namely Nb3Sn superconducting material is used for PF1/6/7 , while NbTi superconducting material is used for PF2 to PF4. This paper analyzes the mechanical properties of PF coils from the aspect of electromagnetic-structure, evaluates the structural strength of PF magnet components, including jacket, insulation, helium inlet/outlet, joints, et al. and determines their structural safety. In terms of thermal hydraulic, the heat loads of the magnet are analyzed first, and then the thermal hydraulic safety of the magnet under the normal operation and the quench condition is analyzed based on the GANDALF program. In terms of electrical safety, the operating voltage and failure voltage due to power supply or ground fault are analyzed. The results of structure, thermal and electrical evaluation can determine that the design of PF coils are safe and reliable.
