Coupling and near-field simulations of ion-cyclotron antennas: Numerical validation of the perfectly matched layer technique for several density profiles

A simplified, flat, plasma-loaded, ion-cyclotron antenna has been simulated using three different modeling approaches and a comparison of simulation outputs is presented in this paper. Several plasma profiles with different density gradients and distances between the antenna and the cutoff density have been used as benchmark for the numerical simulations, which have been run at 30 MHz by means of two tools. The one is the TOrino Polythecnic Ion-Cyclotron Antenna (TOPICA) code that has been repeatedly used and validated for this type of problems. The other tool is the finite-element method (FEM) of a commercial software, where inhomogeneous anisotropic materials can be defined and the perfectly matched layer technique can be adopted. In this tool, two models of antenna load have been implemented: an equivalent dielectric, locally matching the perpendicular propagation constant of the fast wave in the plasma, and a cold plasma model. The simulation results by such models are compared with the results by TOPICA, which relies on a 1-D inhomogeneous, hot plasma.