Study of Space Charge Potential for Propagation of Plasma-Assisted Electron Beam

This article presents a 2-D simulation study of an electron beam profile inside the drift space of a plasma-assisted slow wave structure (SWS) suitable for the generation of sub-terahertz (THz) radiation. The studies have been performed using the particle-in-cell (PIC) simulation software, OOPIC Pro. The realization of high-power sub-THz radiation from vacuum electron devices (VEDs) mainly requires a focused electron beam with high current density and high energy. The beam characteristics inside the W -band SWS have been studied for various parameters, such as the pressure ( P ) of the background gas, beam current ( <tex-math notation="LaTeX">I_b</tex-math> ), and the accelerating voltage <tex-math notation="LaTeX">(V_a</tex-math> ) applied to the beam electrons. The major role of the three parameters on the electron beam profile inside the SWS has been investigated for the wide range with pressure ranging from 1 to 20 Pa, accelerating voltage ranging from 20 to 35 kV, and beam current from 1 to 20 A. Out of these three parameters, gas pressure above 10 Pa and beam current around 1 A are dominant parameters in controlling the profile of the focused electron beam for the applied gap voltage higher than 20 kV.