Projection ablation lithography cathode for high-current, relativistic magnetron

Initial results are presented of an innovative cathode operating in a relativistic magnetron powered by an accelerator with parameters: −0.3 MV, 1–10 kA, and 0.5 μs pulse length. This cathode is fabricated by ablating a pattern on the cathode using a KrF laser. This projection ablation lithography (PAL) cathode has demonstrated fast current turn-on and microwave startup times have decreased from an average of 193 to 118 ns. The pulselength of 1 GHz microwave oscillation has increased from a 144 ns average to 217 ns. With these improvements in microwave startup and pulse length, the microwave power has approximately remained the same compared to the previously used cloth cathodes. A new triple-azimuthal emission region is tested as means of prebunching the electrons (“cathode priming”) into the three spokes desired for pi mode operation in a six-cavity magnetron. The Tri-PAL cathode priming results in the fastest startup and highest efficiency of relativistic magnetron microwave generation.