Particle simulation of lower hybrid waves in tokamak plasmas

TL;DR

This paper presents comprehensive particle simulations of lower hybrid waves in tokamak plasmas, validating theoretical predictions and exploring wave propagation, damping, and mode conversion phenomena with realistic plasma parameters.

Contribution

It introduces fully kinetic ion and drift kinetic electron simulations with realistic mass ratios, providing detailed insights into wave behavior and electromagnetic mode conversion in toroidal geometry.

Findings

Simulation results agree with analytic theory on wave frequency and damping.

Wave propagates faster on the high field side, matching ray tracing.

Electromagnetic mode conversion observed at the plasma boundary.

Abstract

Global particle simulations of the lower hybrid waves have been carried out using fully kinetic ions and drift kinetic electrons with a realistic electron-to-ion mass ratio. The lower hybrid wave frequency, mode structure, and electron Landau damping from the electrostatic simulations agree very well with the analytic theory. Linear simulation of the propagation of a lower hybrid wave-packet in the toroidal geometry shows that the wave propagates faster in the high field side than the low field side, in agreement with a ray tracing calculation. Electromagnetic benchmarks of lower hybrid wave dispersion relation are also carried out. Electromagnetic mode conversion are observed in toroidal geometry, slow waves are launched at the plasma boundary and converts to fast waves at the mode conversion layer, which is consistent with linear theory.