Design and Analysis of a Conduction-Cooled Superconducting Magnet for 30 kW Class Gyrotron

The purpose of this paper is to design and analyze the conduction cooled superconducting magnet for 30 kW class gyrotron. The superconducting magnet for gyrotron provides the central field of 3.57 T to obtain the electron spin resonance frequency of 95 GHz and the high field uniformity so that the electron beam fired from the electron gun can be concentrated on the resonant cavity without scattering of electron beam. For designing the superconducting magnets for gyrotron, the minimum propagation zone and the minimum quench energy of the superconductor composed of NbTi and copper were investigated. Also, the various shapes of superconducting magnet for gyrotron were designed with the given superconductor. The constraint conditions are the central field of magnet should be more than 4.0 T and the field nonhomogeneity should be less than 0.1% at z = ±0.1 m. The objective function is to minimize the amount of the superconductor. The central field and the field non-homogeneity, and the amount of the superconductor of the superconducting magnet for 30 kW class gyrotron were achieved according to the inner and outer diameter, the height of superconducting magnet, and the interval between elementary coils. The characteristics of the designed superconducting magnet were compared with those of the multi-physics analysis using commercial software.