A High-Efficiency Megawatt-Class Nonrelativistic Magnetron

Numerical simulations of a prototype conventional magnetron capable of an RF output power exceeding 1.3 MW at peak efficiency greater than 87% for relatively low diode voltages of ~ 40 kV are presented. Virtual prototyping of the magnetron design is carried out on massively parallel architecture utilizing the 3-D improved concurrent electromagnetic particle-in-cell code. Simulations demonstrate that the magnetron is capable of stable and robust oscillations in the π mode at saturation with negligible mode competition at 912 MHz over a range of magnetic fields extending from B = 0.18 T to B = 0.275 T and voltages ranging from 37-56 kV. RF Output power ranged from 400 kW-1.5 MW over these voltages with efficiencies typically above 85%. Oscillations in the π mode follow the Buneman-Hartree resonance curve for all magnetic fields sampled with a window of π-mode oscillations typically extending over 6 kV. Electron back bombardment of the cathode as well as collisions with the slow wave structure acted as major loss mechanisms.