Energetic electron transport in magnetic fields with island chains and stochastic regions

E.G. Kostadinova; D.M. Orlov; M. Koepke; F. Skiff; M.E. Austin

doi:10.1017/S0022377823000879

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Energetic electron transport in magnetic fields with island chains and stochastic regions

Journal article

Open access

Peer reviewed

Energetic electron transport in magnetic fields with island chains and stochastic regions

E.G. Kostadinova, D.M. Orlov, M. Koepke, F. Skiff and M.E. Austin

Journal of plasma physics, Vol.89(4), 905890420

09/04/2023

DOI: 10.1017/S0022377823000879

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Abstract

This paper investigates energetic electron transport in magnetized toroidal plasmas with magnetic fields characterized by island chains and regions of stochastic field lines produced by coil perturbations. We report on experiments performed in the DIII-D tokamak, which utilize electron cyclotron heating and current drive pulses to ‘tag’ electron populations within different locations across the discharge. The cross-field transport of these populations is then inferred from electron cyclotron emission measurements and gamma emission signals from scintillator detectors. Two types of energetic particles are distinguished and discussed: non-relativistic suprathermal electrons and relativistic runaway electrons. The magnetic field topology in each discharge is reconstructed with field-line tracing codes, which are also used to determine the location and scale of magnetic islands and stochastic regions. Comparison of simulations and experiments suggests that suprathermal transport is suppressed when the tagging is performed at a smaller radial location than the location of the $q = 1$ island chain and enhanced otherwise. Here q is the safety factor. We further demonstrate that increasing the width of the stochastic region within the edge plasma yields enhancement of the suprathermal electron transport.

anomalous diffusion

energetic electrons

field stochasticity

magnetic islands

DIII-D tokamak

Details

Title: Subtitle: Energetic electron transport in magnetic fields with island chains and stochastic regions
Creators: E.G. Kostadinova - Auburn University
D.M. Orlov - University of California San Diego
M. Koepke - West Virginia University
F. Skiff - University of Iowa
M.E. Austin - The University of Texas at Austin
Resource Type: Journal article
Publication Details: Journal of plasma physics, Vol.89(4), 905890420
DOI: 10.1017/S0022377823000879
ISSN: 0022-3778
eISSN: 1469-7807
Publisher: Cambridge University Press
Number of pages: 31
Grant note: DOI: 10.13039/100000015, name: U.S. Department of Energy, award: DE-FG02-05ER54809; DOI: 10.13039/100000015, name: U.S. Department of Energy, award: DE-SC0021405, DE-FG02-97ER54415, DE-FC02-04ER5; DOI: 10.13039/100000015, name: U.S. Department of Energy, award: DE-SC0023061
Language: English
Date published: 09/04/2023
Academic Unit: Physics and Astronomy
Record Identifier: 9984461803702771

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