Optimizing the inner diameter of reflector for high-power microwaves generation in multivircator

In this investigation, we developed an axial virtual cathode oscillator (vircator) by introducing a dielectric reflector within the downstream region of the waveguide. The objective was to optimize the inner diameter for the efficient generation of high-power microwaves from a multivircator. The reflector's inner diameter was systematically adjusted to 0, 2, 4, 6, 8, 10, and 12 cm. Through comprehensive particle-in-cell simulations, it was noticed that the maximum peak power was achieved when the reflector's inner diameter was set at 2 cm, Moreover, the analysis of the phase space of all electrons reveals a dependency on the inner diameter of the reflector for the formation of the VC2. It is crucial to emphasize that when the inner diameter of the reflector exceeds the diameter of the physical cathode (9 cm), VC2 formation does not occur.

I. Introduction

High-power microwave (HPM) sources remain of interest to research scientists due to their diverse range of applications [1], [2]. The virtual cathode oscillator (vircator), a promising HPM source, has been a subject of active research for the past 46 years. Recently, vircator has been utilized to investigate the biological effect of HPM [3]–[7]. The vircator, characterized by its simplicity in construction and independence from an external magnetic field for operation, exhibits the capacity to generate microwaves at gigawatt levels, the same as various other HPM sources [8], [9]. The vircator has historically suffered with lower efficiency. Many attempts have been made to improve its efficiency. However, the efficiency remained limited below 15% with single VC (VC₁) [10]–[12]. The enhancement of HPM generation efficiency in the vircator can be achieved through two primary approaches. Firstly, modification in the geometries and components of the device. Secondly, a configuration within the beam that facilitates the formation of multiple VCs or multvircators should be implemented.