Vortex Electromagnetic Wave Propagation in Magnetized Plasma

Based on the finite-difference time-domain (FDTD) model in the cylindrical coordinate, this article has studied the propagation characteristics of vortex electromagnetic waves (VEMW) in magnetized plasma. To more clearly characterize VEMW, this article has also studied the propagation of VEMW in a vacuum and the results show that VEMW in the vacuum can maintain vortex state and propagate in the direction of antenna radiation. In the magnetized plasma, VEMW is reflected at the cut-off height of each mode, and standing waves occur when the propagation is stable. The vortex state is distorted mainly near the center point, which is particularly serious in the extraordinary wave propagation region. In addition, the orbital angular momentum (OAM) density in magnetized plasma is no longer conserved as in vacuum, and there is a value of OAM density near the center point, which may be related to the collective motion of electrons. Due to the nonlinear interaction between VEMW and plasma, the plasma also presents a vortex state. This propagation model of VEMW can provide some theoretical support for the application of VEMW in ionospheric heating and shortwave communication.