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Title: The sensitivity of tokamak magnetohydrodynamics stability on the edge equilibrium

Abstract

Due to the X-point singularity, the safety factor tends to infinity as approaching to the last closed flux surface. The numerical treatments of the near X-point behavior become challenging both for equilibrium and stability. The usual solution is to cut off a small fraction of edge region for system stability evaluation or simply use an up-down symmetric equilibrium without X-point as an approximation. In this work, we assess the sensitivity of this type of equilibrium treatments on the stability calculation. It is found that the system stability can depend strongly on the safety factor value (qa) at the edge after the cutting-off. When the edge safety factor value falls in the vicinity of a rational mode number (referred to as the resonant gap), the system becomes quite unstable due to the excitation of the peeling type modes. Instead, when the edge safety factor is outside the resonant gaps, the system is much more stable and the predominant modes become the usual external kink (or ballooning and infernal) type. It is also found that the resonant gaps become smaller and smaller as qa increases. The ideal magnetohydrodynamic peeling ballooning stability diagram is widely used to explain the experimental observations, and themore » current results indicate that the conventional peeling ballooning stability diagram based on the simplified equilibrium needs to be reexamined.« less

Authors:
ORCiD logo [1];  [1];  [1]
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  1. Univ. of Texas, Austin, TX (United States)
Publication Date:
Research Org.:
Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1497845
Grant/Contract Number:  
FG02-04ER54742
Resource Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 10; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Zheng, L. J., Kotschenreuther, M. T., and Valanju, P. The sensitivity of tokamak magnetohydrodynamics stability on the edge equilibrium. United States: N. p., 2017. Web. doi:10.1063/1.4986036.
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Zheng, L. J., Kotschenreuther, M. T., & Valanju, P. The sensitivity of tokamak magnetohydrodynamics stability on the edge equilibrium. United States. https://doi.org/10.1063/1.4986036
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Zheng, L. J., Kotschenreuther, M. T., and Valanju, P. Wed . "The sensitivity of tokamak magnetohydrodynamics stability on the edge equilibrium". United States. https://doi.org/10.1063/1.4986036. https://www.osti.gov/servlets/purl/1497845.
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@article{osti_1497845,
title = {The sensitivity of tokamak magnetohydrodynamics stability on the edge equilibrium},
author = {Zheng, L. J. and Kotschenreuther, M. T. and Valanju, P.},
abstractNote = {Due to the X-point singularity, the safety factor tends to infinity as approaching to the last closed flux surface. The numerical treatments of the near X-point behavior become challenging both for equilibrium and stability. The usual solution is to cut off a small fraction of edge region for system stability evaluation or simply use an up-down symmetric equilibrium without X-point as an approximation. In this work, we assess the sensitivity of this type of equilibrium treatments on the stability calculation. It is found that the system stability can depend strongly on the safety factor value (qa) at the edge after the cutting-off. When the edge safety factor value falls in the vicinity of a rational mode number (referred to as the resonant gap), the system becomes quite unstable due to the excitation of the peeling type modes. Instead, when the edge safety factor is outside the resonant gaps, the system is much more stable and the predominant modes become the usual external kink (or ballooning and infernal) type. It is also found that the resonant gaps become smaller and smaller as qa increases. The ideal magnetohydrodynamic peeling ballooning stability diagram is widely used to explain the experimental observations, and the current results indicate that the conventional peeling ballooning stability diagram based on the simplified equilibrium needs to be reexamined.},
doi = {10.1063/1.4986036},
journal = {Physics of Plasmas},
number = 10,
volume = 24,
place = {United States},
year = {2017},
month = {10}
}
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Journal Article:
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Publisher's Version of Record
https://doi.org/10.1063/1.4986036
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Cited by: 2 works
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Figures / Tables:

Figure 1 Figure 1: Cross section of the ITER H-mode confinement as computed by the CORSICA code. The radial grids are compacted at the rational surfaces by the AEGIS code.
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Works referenced in this record:

Currents in the scrape-off layer of diverted tokamaks
journal, October 1989

ELMs and constraints on the H-mode pedestal: peeling–ballooning stability calculation and comparison with experiment
journal, January 2004

Investigation of the n   =  1 resistive wall modes in the ITER high-mode confinement
journal, April 2017

Numerical studies of edge localized instabilities in tokamaks
journal, April 2002

  • Wilson, H. R.; Snyder, P. B.; Huysmans, G. T. A.
  • Physics of Plasmas, Vol. 9, Issue 4
  • DOI: 10.1063/1.1459058

Low- n magnetohydrodynamic edge instabilities in quiescent H-mode plasmas with a safety-factor plateau
journal, May 2013

Stability criteria for edge flute modes in the two‐fluid regime
journal, May 1993

  • Zheng, L. ‐J.
  • Physics of Fluids B: Plasma Physics, Vol. 5, Issue 5
  • DOI: 10.1063/1.860879

Progress in the ITER Physics Basis
journal, June 2007

Neoclassical conductivity and bootstrap current formulas for general axisymmetric equilibria and arbitrary collisionality regime
journal, July 1999

  • Sauter, O.; Angioni, C.; Lin-Liu, Y. R.
  • Physics of Plasmas, Vol. 6, Issue 7
  • DOI: 10.1063/1.873240

Stability Criterion for Arbitrary Hydromagnetic Equilibria
journal, January 1962

  • Greene, John M.; Johnson, John L.
  • Physics of Fluids, Vol. 5, Issue 5
  • DOI: 10.1063/1.1706651

Hydromagnetic stability of tokamaks
journal, January 1978

Theory-based model for the pedestal, edge stability and ELMs in tokamaks
journal, February 2006

Development and validation of a predictive model for the pedestal height
journal, May 2009

  • Snyder, P. B.; Groebner, R. J.; Leonard, A. W.
  • Physics of Plasmas, Vol. 16, Issue 5
  • DOI: 10.1063/1.3122146

AEGIS: An adaptive ideal-magnetohydrodynamics shooting code for axisymmetric plasma stability
journal, January 2006

Simulation of the hybrid and steady state advanced operating modes in ITER
journal, August 2007

The general “peeling” instability
journal, February 1975

Edge stability of the ELM-free quiescent H-mode on DIII-D
journal, November 2005

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    Figure 1 (p. 3)figure
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