Dispersion and damping of ion acoustic wave in deuterium–tritium fusion plasmas with slowing-down distributed  α  particles

F F Lu,S Q Liu

doi:10.1063/5.0045555

Abstract

The dispersion and damping rate of the ion acoustic waves (IAWs) in deuterium–tritium (D–T) fusion plasmas with slowing-down distributed α particles are investigated within the framework of kinetic theory. It is shown that the concentration of α particles has an important effect on IAWs. The frequency of IAWs decreases as the α concentration increases. Inversely, the damping rate increases as the α concentration increases. The results for slowing-down distributed α particles are compared with those obtained when α particles are assumed to have an equivalent Maxwellian distribution.

Highlights

Over the past decades, as one of the key missions to prove the feasibility of fusion as a new energy source, the study of the transport and confinement of fast ions and, in particular, fusion born α particles in burning plasmas has received special interest
In order to show the differences in ion acoustic waves (IAWs) between the slowing-down distributed α particle and the Maxwellian distributed α particle, we present the dispersion and damping rates of IAWs under the assumption that α particles follow the equivalent Maxwellian distribution
Under the assumption that vtD, vtT ≪ ω/k∥ ≪ vtα, vte and k ρj ≪ 1, the dispersion and damping rate of IAWs have been derived from the kinetic theory in the D–T fusion plasmas with slowing-down distributed α particles

Summary

INTRODUCTION

As one of the key missions to prove the feasibility of fusion as a new energy source, the study of the transport and confinement of fast ions and, in particular, fusion born α particles in burning plasmas has received special interest. Lauber and Gunter investigated the Landau damping of low-frequency modes in tokamak plasmas according to gyrokinetic theory. They have found that the ion acoustic branch is severely damped and can turn into the electrostatic drift branch. The Landau damping of IAWs is well studied for plasma particles obeying Maxwellian distribution. We investigate the dispersion and damping rate of IAWs in D–T fusion plasmas on the basis of the kinetic theory..

The longitudinal dielectric function

Dispersion and damping rate of IAWs

RESULTS AND DISCUSSIONS

CONCLUSION