Toroidal Alfvén eigenmodes in a tokamak with a population of high-energy large-orbit ions

Abstract

The effect of the density gradient of high-energy ions moving in large magnetic drift orbits is studied analytically in the context of the problem of toroidal Alfven eigenmodes (TAEs) in a tokamak. It is found that, when the population of such ions is not too small, this effect can substantially modify standard TAEs and give rise to new types of TAEs, which are called TAEs-H, TAEs-H+s, and TAEs-H−s. The continual dissipation of TAEs is investigated with allowance for the effect in question. It is shown that the dissipation acts to dampen all the TAE types under consideration.