Optimization Design of Flat-Top Pulsed Magnet for an 800-GHz Second Harmonic Gyrotron

This article proposes a technique of flat-top magnetic field for the goal of high-frequency gyrotron with a pulse duration of several hundred milliseconds. A 14.8-T flat-top pulsed magnet is designed for an 800-GHz second harmonic gyrotron. The magnet is energized by a battery bank with a bypass circuit to achieve a 620-ms pulse duration. To fulfill the requirements of the gyrotron and magnet power supply, the genetic algorithm NSGA-II has been used in the multiobjective optimization of the field distribution and power dissipation of the magnet. The Helix magnet with the layered reinforcement technique is introduced to address the problems of stress and temperature rise. The proposed scheme in this article can be easily extended to most pulsed magnets for gyrotrons.