Particle-in-Cell Simulation and Analysis of 28-Vane Megawatt-Class Pulsed Power Coaxial Magnetron in X-Band

This article presents the design and analysis of a 28-vane megawatt-class pulsed power coaxial magnetron operating in X-band for medical linear accelerator (LINAC) applications. The systematic design procedure of the coaxial magnetron is presented. The proposed coaxial magnetron is analyzed using particle-in-cell (PIC) simulations. The output is taken from the standard WR112 waveguide through a rectangular slot in the outer wall of the coaxial cavity. The maximum total efficiency of 62.04% is obtained at 9.2987 GHz, having a 2.12-MW peak output power for stable π-mode operation. The π-mode operation is determined by 14 spokes of electrons in the PIC simulation. Electronic efficiency and circuit efficiency of the designed coaxial magnetron are obtained as 73.86% and 84%, respectively. The output peak power can be enhanced by optimizing the applied magnetic field in the operating region of π-mode. Total efficiency is improved by 2.74% by changing the shape of the cathode end hats from conventional to conical. The dielectric properties of the slot-mode suppressor are optimized based on the output performance of coaxial magnetron. The optimal values of dielectric constant and loss tangents are obtained as 21 and 0.08, respectively. The frequency-tuning characteristics of the magnetron are also analyzed, and the tuning range is obtained as 9.2987 GHz ± 20 MHz.