Numerical Simulations of a Relativistic Inverted Magnetron

Abstract

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 π mode at axial magnetic fields of the order of ~0.1 T. ICEPIC simulations demonstrate that the inverted magnetron is capable of fast start-up, mitigation of mode competition, π-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.