Frequency chirping of energetic particle driven modes in tokamaks; Self-consistent modelling and simulation
type: CreativeWork
description: Long range frequency chirping waves have been observed in various plasma experiments. Theoretical toy models and simulations show that the nonlinear saturation of an initially unstable plasma wave driven by energetic particles may lead to the emergence of chirping waves. In toroidal configurations, these waves can lead to ejection of the particles from the hot core of the plasma and degrade the machine performance. Therefore, it is essential to develop theory and simulation models to better understand and control chirping waves in future fusion plasmas, such as ITER. Fast particles of tokamaks can destabilize plasma waves. Previous numerical simulations have revealed that an isolated Alfven eigenmode can evolve into chirping signals if the mode is subject to intrinsic damping into the cold plasma. In 1997, Berk-Breizman and co-workers studied the nonlinear stage of an excited electrostatic plasma wave where chirping signals were observed and interpreted as Bernstein-Greene-Kruskal waves with sweeping frequencies. These chirping waves are associated with coherent structures, the so-called "holes" and "clumps", in phase space of energetic particles. Such structures found to move adiabatically which implies the particles can be carried with the waves; so called convective transport. During long ranges of frequency chirping, the spatial profile of the wave can change considerably and hence new models are required to study long range frequency chirping of Alfvenic perturbations. In 2010, a 1D electrostatic nonperturbative model was developed by Breizman for an adiabatic study of chirping waves as a 1D paradigm of their electromagnetic counterparts. In order to build more realistic models, nonperturbative theory needs to be extended to electromagnetic waves and also fast particle orbital dynamics should be captured. In this work, a model is developed to investigate the effect of fast particle dynamics in tokamaks using a 1D description. This new trapped/passing model demo…
abstract: Long range frequency chirping waves have been observed in various plasma experiments. Theoretical toy models and simulations show that the nonlinear saturation of an initially unstable plasma wave driven by energetic particles may lead to the emergence of chirping waves. In toroidal configurations, these waves can lead to ejection of the particles from the hot core of the plasma and degrade the machine performance. Therefore, it is essential to develop theory and simulation models to better understand and control chirping waves in future fusion plasmas, such as ITER. Fast particles of tokamaks can destabilize plasma waves. Previous numerical simulations have revealed that an isolated Alfven eigenmode can evolve into chirping signals if the mode is subject to intrinsic damping into the cold plasma. In 1997, Berk-Breizman and co-workers studied the nonlinear stage of an excited electrostatic plasma wave where chirping signals were observed and interpreted as Bernstein-Greene-Kruskal waves with sweeping frequencies. These chirping waves are associated with coherent structures, the so-called "holes" and "clumps", in phase space of energetic particles. Such structures found to move adiabatically which implies the particles can be carried with the waves; so called convective transport. During long ranges of frequency chirping, the spatial profile of the wave can change considerably and hence new models are required to study long range frequency chirping of Alfvenic perturbations. In 2010, a 1D electrostatic nonperturbative model was developed by Breizman for an adiabatic study of chirping waves as a 1D paradigm of their electromagnetic counterparts. In order to build more realistic models, nonperturbative theory needs to be extended to electromagnetic waves and also fast particle orbital dynamics should be captured. In this work, a model is developed to investigate the effect of fast particle dynamics in tokamaks using a 1D description. This new trapped/passing model demo…
author: Hezaveh Hesar Maskan, Hooman
language: en_AU
date published: 2022
date modified: 2026-07-24T00:54:41Z
provider: Australian National University
publisher: Networked Digital Library of Theses and Dissertations
type: WebPage
source organization: Australian National University

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property ID: Handle
value: http://hdl.handle.net/1885/258997