Turbulent transport of fast ions in tokamak plasmas in the presence of resonant magnetic perturbations

TL;DR

This paper investigates how resonant magnetic perturbations influence turbulent fast ion transport in tokamaks, revealing effects of finite Larmor radius, magnetic perturbation amplitude, and turbulence coupling on diffusion.

Contribution

It introduces a theoretical test-particle transport model combined with numerical simulations to analyze fast ion diffusion under magnetic perturbations in tokamaks.

Findings

Finite Larmor radius reduces transport algebraically.

Magnetic perturbation amplitude increases transport.

A nonlinear coupling enhances radial diffusion.

Abstract

The effects of resonant magnetic perturbations on the turbulent transport of fast ions in tokamak devices are investigated using a theoretical transport model of test-particle type. The direct numerical simulation method is used to compute, via the transport model, the diffusion coefficients. The numerical results are in good agreement with other, analytically derived, estimations. It is found that finite Larmor radius effects decrease algebraically the transport, while the amplitude of magnetic perturbations has an opposite effect. In the presence of stochastic dynamics, the asymmetric toroidal magnetic field induces a small, radial, outward pinch. A synergistic mechanism of non-linear coupling between turbulence and magnetic perturbations enhances the radial diffusion. General scaling laws are proposed for the transport coefficients.