Stochastic diffusion of energetic ions due to lower hybrid waves

Abstract

This paper discusses the interaction between energetic ions and lower hybrid waves in tokamak plasmas, presenting a numerical analysis which employs a quasilinear formalism appropriated for the situation in which ion stochastic di usion occurs. The results show that signi cant w ave-particle interaction may take place when a population of energetic ions is present in the plasma, in partial agreement with evidence from experimental results available in the literature.

Stochastic diffusion of energetic ions due to incoherent lower hybrid waves

“…When the threshold condition is satisfied a quasilinear formalism can be derived and employed to describe the stochastic diffusion which occurs in velocity space [2]. Using quasilinear analysis, significant waveparticle interaction between energetic ions and lower hybrid (LH) waves has been indeed demonstrated to occur [6,7].…”

Interaction between lower hybrid waves and energetic ions in a tokamak system

“…We have already investigated some features of this subject, starting with a discussion on the threshold condition for stochastic ion diffusion due to LH waves, originated from the analysis by Karney [2], and continuing by the application of a two-dimensional quasilinear formulation which was able to follow the time evolution of the electron and ion distribution functions under the action of LH and IC waves, and collisions [17,18]. In this investigation the LH spectrum was assumed to be very narrow, such that a monochromatic wave could be assumed for the evaluation of the LH diffusion coefficient, according to the Karney proposal [2].…”