High-power magnetron experiments and numerical simulation

High power microwave devices are of interest for applications to pulse compression in cavities, as electromagnetic pumps for free-electron lasers, air breakdown studies, advanced high energy accelerators and plasma heating for magnetic-confinement fusion. Two experimental approaches have been pursued to obtain high-power microwave radiation from high voltage magnetrons. In one approach at MIT and Lawrence Livermore studies were performed on small-gap high voltage six and eight vane magnetrons. These devices, operating at 700 kV to 1 MV, yielded 300 MW to 4 GW of power at 3–4 GHz for pulse durations of up to 50 ns. Another approach, pursued at NRL, has used large gaps with an inverted 54-vane structure to achieve potential long-pulse operation. This experiment has produced 500–800 MW at 3.2 GHz in a 50 ns pulse with an applied voltage of 600 kV. Work has been initiated on extending the pulse duration to 250 ns (and ultimately to > 1 μs duration). A summary of the experimental results is presented.