Relativistic magnetron driven by a microsecond E-beam accelerator with a ceramic insulator

Relativistic magnetron experiments performed on a six-cavity device have generated over 300 MW total microwave power near 1 GHz. These experiments were driven by the long-pulse electron beam from an accelerator with parameters as follows: voltage of *300 kV, current of 1-10 kA, and typical pulselength of 0.5 ms. This paper reports investigations of high-power microwave generation, mode competition, and pulse shortening for the relativistic magnetron with a ceramic insulator compared to a plastic insulator. The ceramic insulator improves the vacuum by a factor of ten (to 10^*7 torr range) and flattens the voltage of the accelerator. Relativistic magnetron performance with the ceramic insulator shows increased microwave power and pulselength over the plastic insulator. Effects of RF breakdown in the extraction waveguide on peak microwave power and pulselength are also investigated by utilizing SF₆ in one or both of the extraction waveguides.