Simulation of electron acceleration in a plasma-filled twisted elliptical waveguide: effect of twist angle

Abstract

This study investigates the acceleration and dynamics of an electron injected into a plasma-filled, twisted elliptical waveguide with perfectly conducting walls, using COMSOL Multiphysics simulations. The electromagnetic fields inside the waveguide are first obtained from the electromagnetic solution, and the subsequent electron field interaction is analyzed using the relativistic momentum and energy equations. In the cold-plasma-filled twisted elliptical waveguide, the electron kinetic energy, acceleration gradient, deflection angle, trajectory, velocity components, and force components are presented and compared for different total twist angles. The study is then extended to a magnetized plasma-filled twisted elliptical waveguide under an externally applied static axial magnetic field. For this configuration, the electromagnetic field distributions, dispersion characteristics, scattering parameters, and electron dynamical behavior are analyzed. The results show that the twist angle significantly affects electron acceleration in both cold and magnetized plasma configurations. Within a certain range, increasing the twist angle enhances the electron kinetic energy and acceleration gradient, whereas further increase beyond this range reduces the energy. The corresponding changes in trajectory, deflection angle, velocity, and force components show that the twist rate plays an important role in controlling the interaction between the injected electron and the electromagnetic fields. Therefore, the proposed plasma-filled twisted elliptical waveguide provides a controllable structure to regulate and enhance the kinetic energy of an injected electron.