Kinetic simulation of the O-X conversion process in dense magnetized plasmas

TL;DR

This paper presents a kinetic particle simulation of the O-X conversion process in dense magnetized plasmas, demonstrating the efficiency and details of wave conversion in the TJ-II stellarator using the XOOPIC code.

Contribution

It introduces a kinetic particle model simulation of the O-X conversion process that aligns well with full wave models and optimizes the process parameters.

Findings

O-X conversion observed clearly in simulations

Conversion efficiency reaches 66% at optimal angle

Simulation results agree with previous full-wave models

Abstract

The ordinary-extraordinary-Bernstein (O-X-B) double conversion is considered and simulated with a kinetic particle model vs full wave model for parameters of the TJ-II stellarator. This simulation has been done with the particle-in-cell code, XOOPIC (X11-based object-oriented particle-incell). XOOPIC is able to model the non-monotonic density and magnetic profile of TJ-II. The first step of conversion, O-X conversion, is observed clearly. By applying some optimizations such as increasing the number of computational particles in the region of the X-B conversion, the simulation of the second step is also possible. By considering the electric and magnetic components of launched and reflected waves, the O-mode wave and the X-mode wave can be easily detected. Via considering the power of launched O-mode wave and converted X-mode wave, the efficiency of O-X conversion for the best theoretical launch angle is obtained, which is in good agreement with previous computed efficiencies via full-wave simulations. For the optimum angle of 47? between the wave-vector of the incident O-mode wave and the external magnetic field, the conversion efficiency is 66%.