Three-Dimensional Simulations of Magnetic Priming of a Relativistic Magnetron

Using a hybrid approach, 3-D simulations of magnetic priming of a relativistic magnetron have been performed. The primed magnetic field values were calculated using a magnetostatics code (Magnum) and then imported into a particle-in-cell code (Magic PIC) and run for the case of a six-vane relativistic magnetron. The magnetically perturbative structures chosen for implementation in these simulations were sets of three high-permeability wires of various lengths, which would be placed within the cathode, the anode, or, in the combined case, both the cathode and anode. In the best-performing cathode-wire case (three 4-cm wires), magnetic priming was found to reduce the start-oscillation time of the magnetron to 50% that of the unprimed case. When wires were embedded in both the cathode and the anode, the best-performing case (4-cm cathode wires and 4-cm anode wires) was found to start oscillating at 30% of the start-oscillation time of the unprimed case. The cases of magnetically primed magnetrons were found to exhibit slightly reduced equilibrium power levels, compared with the unprimed case.