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Title: Edge-localized-modes in tokamaks

Abstract

Edge-localized-modes (ELMs) are a ubiquitous feature of H-mode in tokamaks. When gradients in the H-mode transport barrier grow to exceed the MHD stability limit the ELM instability grows explosively, rapidly transporting energy and particles onto open field lines and material surfaces. Though ELMs provide additional particle and impurity transport through the H-mode transport barrier, enabling steady operation, the resulting heat flux transients to plasma facing surfaces project to large amplitude in future low collisionality burning plasma tokamaks. Measurements of the ELM heat flux deposition onto material surfaces in the divertor and main chamber indicate significant broadening compared to inter-ELM heat flux, with a timescale for energy deposition that is consistent with sonic ion flow and numerical simulation. Comprehensive ELM simulation is highlighting the important physics processes of ELM transport including parallel transport due to magnetic reconnection and turbulence resulting from collapse of the H-mode transport barrier. Encouraging prospects for ELM control and/or suppression in future tokamaks include intrinsic modes of ELM free operation, ELM triggering with frequent small pellet injection and the application of 3D magnetic fields.

Authors:
 [1]
  1. General Atomics, PO Box 85608, San Diego, California 92186-5608 (United States)
Publication Date:
OSTI Identifier:
22303604
Resource Type:
Journal Article
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 21; Journal Issue: 9; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1070-664X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; DIFFUSION BARRIERS; DIVERTORS; EDGE LOCALIZED MODES; ENERGY ABSORPTION; ENERGY LOSSES; FIRST WALL; HEAT FLUX; H-MODE PLASMA CONFINEMENT; MAGNETIC FIELDS; MAGNETIC RECONNECTION; MAGNETOHYDRODYNAMICS; NATURAL GAS DISTRIBUTION SYSTEMS; PELLET INJECTION; PLASMA IMPURITIES; SURFACES; TOKAMAK DEVICES

Citation Formats

Leonard, A. W. Edge-localized-modes in tokamaks. United States: N. p., 2014. Web. doi:10.1063/1.4894742.
Leonard, A. W. Edge-localized-modes in tokamaks. United States. doi:10.1063/1.4894742.
Leonard, A. W. Mon . "Edge-localized-modes in tokamaks". United States. doi:10.1063/1.4894742.
@article{osti_22303604,
title = {Edge-localized-modes in tokamaks},
author = {Leonard, A. W.},
abstractNote = {Edge-localized-modes (ELMs) are a ubiquitous feature of H-mode in tokamaks. When gradients in the H-mode transport barrier grow to exceed the MHD stability limit the ELM instability grows explosively, rapidly transporting energy and particles onto open field lines and material surfaces. Though ELMs provide additional particle and impurity transport through the H-mode transport barrier, enabling steady operation, the resulting heat flux transients to plasma facing surfaces project to large amplitude in future low collisionality burning plasma tokamaks. Measurements of the ELM heat flux deposition onto material surfaces in the divertor and main chamber indicate significant broadening compared to inter-ELM heat flux, with a timescale for energy deposition that is consistent with sonic ion flow and numerical simulation. Comprehensive ELM simulation is highlighting the important physics processes of ELM transport including parallel transport due to magnetic reconnection and turbulence resulting from collapse of the H-mode transport barrier. Encouraging prospects for ELM control and/or suppression in future tokamaks include intrinsic modes of ELM free operation, ELM triggering with frequent small pellet injection and the application of 3D magnetic fields.},
doi = {10.1063/1.4894742},
journal = {Physics of Plasmas},
issn = {1070-664X},
number = 9,
volume = 21,
place = {United States},
year = {2014},
month = {9}
}