Optimization Design of Compact Magnetron Injection Gun of Terahertz Gyrotrons

In this article, a 2.5-D numerical computational model of a magnetron injection gun (MIG) is established. The design principles of the compact MIG of terahertz gyrotrons are investigated, and a design is proposed. In the electric field calculation stage, a multigrid (MG) method combined with successive over-relaxation (SOR) iteration is employed to enhance computational efficiency. The elite strategy-enhanced multiobjective particle swarm optimization (MOPSO) algorithm automatically optimizes the initial MIG toward the target parameter values. Then, a compact MIG of terahertz gyrotrons is designed, with the output electron beam parameters achieving the design targets: a pitch ratio of 1.3 and a velocity spread of 3%. Its total axial length is less than 160 mm. These results demonstrate the efficiency and effectiveness of the proposed method.