Numerical Simulations of a Relativistic Inverted Magnetron

A new design for an inverted magnetron is presented and modeled both analytically, using a single particle smooth bore relativistic approach, and numerically, using a massively parallel electromagnetic particle-in-cell code, Improved Concurrent Electromagnetic Particle-In-Cell (ICEPIC) code. Analysis and simulation confirm that the inverted magnetron design presented here is capable of oscillating in the pi mode at axial magnetic fields of the order of similar to 0.1 T. ICEPIC simulations demonstrate that the inverted magnetron is capable of fast start-up, mitigation of mode competition, pi-mode dominance, and high output power, of the order of 1 GW in some cases. Moreover, these performance features spanned over a variety of magnetic fields and input voltages. In simulations, the inverted magnetron design presented here demonstrated that end-loss current, a common source of energy leakage in relativistic magnetrons, has been eliminated as a source of energy loss. However, radio frequency output power efficiencies only remained comparable with standard relativistic designs. This was due to poor energy exchange between the particle and field. Thus, a refinement of the slow wave structure may be necessary.