Simulation of the internal kink mode in visco-resistive regimes

TL;DR

This paper uses two-fluid simulations to study how plasma flows, viscosity, and diamagnetic effects influence the nonlinear evolution of the internal kink mode, revealing stabilizing effects and symmetry breaking phenomena.

Contribution

It extends previous RMHD studies by incorporating two-fluid effects, demonstrating their significant impact on mode dynamics and stability in visco-resistive plasma regimes.

Findings

Diamagnetic effects and flows synergistically stabilize the mode.

Novel symmetry breaking in growth rates and saturated states.

Viscosity modifies the mode's real frequency in the linear regime.

Abstract

We present numerical simulation results of the nonlinear evolution of the (1,1) internal kink mode in the presence of various kinds of equilibrium plasma flows. The present studies are carried out in the framework of a two fluid model to extend our past investigations done with a reduced magneto-hydrodynamic (RMHD) model. Two-fluid effects are found to significantly influence the mode dynamics in a number of different ways. In the linear regime diamagnetic effects in combination with flows provide a synergistic stabilizing influence that also carries over to the nonlinear regime. In addition one observes novel symmetry breaking phenomena in the linear growth rates as well as in the nonlinear saturated states of the mode. Our study also explores the influence of strong viscosity on the mode evolution and finds interesting modifications in the real frequency of the mode in the linear regime.