Finite-orbit-width effects on the geodesic acoustic mode in the toroidally rotating tokamak plasma

TL;DR

This paper analytically investigates the Landau damping of geodesic acoustic modes in toroidally rotating tokamak plasmas, considering finite-orbit-width effects up to third order, and compares results with numerical solutions.

Contribution

It introduces a third-order finite-orbit-width resonance effect analysis for GAM damping in rotating tokamak plasmas, enhancing understanding of damping rate dependencies.

Findings

Damping rate decreases with Mach number for small $k_r ho_i$.

Damping rate increases then decreases with Mach number for large $k_r ho_i$.

Analytical results agree well with numerical solutions.

Abstract

The Landau damping of geodesic acoustic mode (GAM) in a torodial rotating tokamak plasma is analytically investigated by taking into account the finite-orbit-width (FOW) resonance effect to the 3rd order. The analytical result is shown to agree well with the numerical solution. The dependence of the damping rate on the toroidal Mach number $M$ relies on $k_r \rho_i$. For sufficiently small $k_r \rho_i$, the damping rate monotonically decreases with $M$. For relatively large $k_r \rho_i$, the damping rate increases with $M$ until approaching the maximum and then decreases with $M$.