Characterization of relativistic magnetron behavior by 3-D PIC simulation

We describe a systematic analysis of relativistic magnetron behavior via direct numerical simulation, which is compared with experimental data from the Physics International (PI) magnetron where possible. Throughout, we have sought to isolate individual physical processes, but even so, we are able to reproduce most features of the experiment qualitatively, and many quantitatively within the limitations of the model. Specifically, we find that magnetron operation is effectively limited to a comparatively small region of parameter space and distant from both the Hull and Buneman-Hartree curves, and further curtailed by mode competition. Where effective operation does occur, we have been able to reproduce the experimentally observed pulse shortening and, on the basis of our simulations, are able to suggest a cure. Our evidence is that comprehensive modeling of magnetrons can facilitate the making of critical design decisions, thereby enabling the devices to meet demanding specifications for power and energy delivery.