3D PIC simulation study of a relativistic, rising sun magnetron

Summary form only given. The magnetron oscillator can be a highly efficient device for generating microwaves. When operated at low voltage (V<100 kV) efficiencies greater than 50% can be achieved. At relativistic voltages (V/spl sim/500 kV), however, the peak efficiency is generally much less than 30%. Results of a recent numerical study of the A6 magnetron suggest that the low efficiencies realized in previous relativistic magnetron experiments were due more to using an inappropriate tube configuration than to relativistic effects. In particular, it was suggested that efficient high power operation at relativistic voltages would require a significant increase in tube dimensions relative to the free-space wavelength of the desired mode. To test this hypothesis we have performed a numerical study of a 14 cavity magnetron oscillator using 3D particle-in-cell (PIC) simulation. The magnetron has an anode diameter to free-space wavelength ratio of about 1:1, and its oscillation frequency is 1.1 GHz.