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Description
An electron cyclotron is to heat a plasma by driving current in a fusion system. This system requires strength and accurate magnetic field distribution for the interaction of the electron beam and radio frequency wave energy. The magnet of the system consists of a conduction-cooled superconducting magnet for 7 T and structures connected with a 2nd stage GM cryo-cooler of 1 W at 4 K for cooling of the magnet. This paper deals with the design of the magnet and conduction-cooling structures considering electrical and thermal stability. The magnet is wound with NbTi conductors. The inner bore of the superconducting coil is 240 mm to obtain the resonance region. Genetic algorithm incorporated with the linear programming is used for the optimal design. The objective function for optimization design of the superconducting coil is considered to minimize the amount of the superconducting wires. Then the design constraints including normal stresses generated by the electromagnetic force, magnet critical current margin, losses under the AC operation (charging/discharging) are also calculated to ensure safe operation of the superconducting magnet. After design, the quench analysis is carried out to verify the heat transfer and thermal stability of the gyrotron magnet. After the design, the 170-GHz gyrotron magnet will be fabricated with an auto-mated winding machine based on to the design results.
