Optimized Design of a 170-GHz Gyrotron Magnet With Thermally Insulated Structures

An electron cyclotron is used to heat plasma by driving current in a fusion system. This system requires a strong and accurate magnetic field distribution for the interaction between the electron beam and the radio frequency wave energy [1]. A superconducting magnet is designed for a 170 GHz gyrotron system here. The magnet is composed of conduction cooled NbTi coils, a GM cryocooler with thermal links, supporters, and a cryostat. The magnet was designed using an optimization method that considered the normal stresses generated by electromagnetic forces, the critical current margin, the axial field profile, and field uniformity and losses under AC operation. A quench analysis was also carried out to ensure the safe operation of the gyrotron magnet. The inner bore of the designed superconducting coil is 200 mm to obtain a proper resonance region. A bobbin and structures for thermal insulation were also designed considering the heat transfer and cooling capacities of the cryocooler. The gyrotron magnet will be manufactured using an automatic winding machine based on these design results.