Kim, E-J and Hollerbach, R orcid.org/0000-0001-8639-0967 (2023) A stochastic model of edge-localized modes in magnetically confined plasmas. Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences, 381 (2242). 20210226. ISSN 1364-503X
Abstract
Magnetically confined plasmas are far from equilibrium and pose considerable challenges in statistical analysis. We discuss a non-perturbative statistical method, namely a time-dependent probability density function (PDF) approach that is potentially useful for analysing time-varying, large, or non-Gaussian fluctuations and bursty events associated with instabilities in the low-to-high confinement transition and the H-mode. Specifically, we present a stochastic Langevin model of edge-localized modes (ELMs) by including stochastic noise terms in a previous ODE ELM model. We calculate exact time-dependent PDFs by numerically solving the Fokker–Planck equation and characterize time-varying statistical properties of ELMs for different energy fluxes and noise amplitudes. The stochastic noise is shown to introduce phase-mixing and plays a significant role in mitigating extreme bursts of large ELMs. Furthermore, based on time-dependent PDFs, we provide a path-dependent information geometric theory of the ELM dynamics and demonstrate its utility in capturing self-regulatory relaxation oscillations, bursts and a sudden change in the system.
This article is part of a discussion meeting issue ‘H-mode transition and pedestal studies in fusion plasmas’.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2023 The Author(s). Published by the Royal Society. All rights reserved. This is an author produced version of an article, published in Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | high-confinement mode; statistical theory; information geometry; self-regulation; time-dependent probability density function; Fokker–Planck equation |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Mathematics (Leeds) > Applied Mathematics (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 06 Jul 2022 15:20 |
Last Modified: | 04 Mar 2023 07:42 |
Status: | Published |
Publisher: | The Royal Society |
Identification Number: | 10.1098/rsta.2021.0226 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:188473 |