Realistic 3-D Particle-In-Cell Simulation of a Medical 2.1 MW 40-Vane X-Band Coaxial Magnetron

Abstract

A medical 2.1 MW 40-vane <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${X}$ </tex-math></inline-formula> -band coaxial magnetron is designed and analyzed using a 3-D particle-in-cell (PIC) simulation. For realistic simulation, the magnetic field profile from the 3-D magnetic circuit and the structure of the output window are included in the simulation. A frequency tuner is located inside the coaxial resonator to control the operating frequency, and the output power is measured at the WR-112 waveguide located behind the output window. Using the operating conditions with an anode voltage of 35.8 kV and a magnetic field of 0.595 T, a maximum output power of 2.1 MW with an efficiency of 53.6% is measured in the stable <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pi $ </tex-math></inline-formula> -mode resulting from the 20-electron spokes. The frequency tuner is moved down and up by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pm 300 \mu \text{m}$ </tex-math></inline-formula> along the axial direction, and the frequency bandwidth is 72 MHz from 9.272 to 9.344 GHz with the tuning parameter of 0.12 MHz/ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> . In addition, the output performance is simulated to investigate the effect of dimensional parameters such as the coupling slot width and transformer length.