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Title: Use of reconstructed 3D equilibria to determine onset conditions of helical cores in tokamaks for extrapolation to ITER

Abstract

The threshold for spontaneous symmetry breaking, which results in growth of m/n = 1/1 helical cores, in tokamaks is determined using VMEC. This model is based on a DIII-D hybrid discharge with helical core, and it predicts ITER (15MA scenario) to operate far in the helical core formation regime. Helical cores can only exist in tokamak discharges with monotonic but low, or reversed q-shear and qmin 1 in the core. The helical core is a saturated internal kink mode; its onset threshold is proportional to (dp/d)/B2t around q = 1. Below the threshold, applied 3-D fields can drive a helical core to finite size, as in DIIID. Above it, a random 3-D kick causes a bifurcation from axisymmetry and excites a spontaneous helical core. Helical cores occur frequently in C-Mod due to impurities; modeling shows the axisymmetric equilibrium becomes unstable at the end of the current ramp up due to the slow current penetration and a resultant reversed shear q-profile, which lowers the threshold. Lastly, a comparison of the helical core onset threshold for discharges from DIII-D, C-Mod and ITER confirms that while DIII-D is marginally stable, C-Mod and especially ITER are highly susceptible to helical core formation.

Authors:
ORCiD logo [1];  [1];  [1]; ORCiD logo [1]; ORCiD logo [1];  [2];  [1];  [3]
+ Show Author Affiliations
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  3. General Atomics, San Diego, CA (United States)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF); Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States); General Atomics, San Diego, CA (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Fusion Energy Sciences (FES)
OSTI Identifier:
1422609
Alternate Identifier(s):
OSTI ID: 1375431
Grant/Contract Number:  
AC05-00OR22725; AC02-09CH11466; FC02-04ER54698
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 58; Journal Issue: 3; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY

Citation Formats

Wingen, A., Wilcox, R. S., Seal, S. K., Unterberg, E. A., Cianciosa, M. R., Delgado-Aparicio, L. F., Hirshman, S. P., and Lao, L. L. Use of reconstructed 3D equilibria to determine onset conditions of helical cores in tokamaks for extrapolation to ITER. United States: N. p., 2018. Web. doi:10.1088/1741-4326/aaa33d.
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Wingen, A., Wilcox, R. S., Seal, S. K., Unterberg, E. A., Cianciosa, M. R., Delgado-Aparicio, L. F., Hirshman, S. P., & Lao, L. L. Use of reconstructed 3D equilibria to determine onset conditions of helical cores in tokamaks for extrapolation to ITER. United States. https://doi.org/10.1088/1741-4326/aaa33d
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Wingen, A., Wilcox, R. S., Seal, S. K., Unterberg, E. A., Cianciosa, M. R., Delgado-Aparicio, L. F., Hirshman, S. P., and Lao, L. L. Mon . "Use of reconstructed 3D equilibria to determine onset conditions of helical cores in tokamaks for extrapolation to ITER". United States. https://doi.org/10.1088/1741-4326/aaa33d. https://www.osti.gov/servlets/purl/1422609.
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@article{osti_1422609,
title = {Use of reconstructed 3D equilibria to determine onset conditions of helical cores in tokamaks for extrapolation to ITER},
author = {Wingen, A. and Wilcox, R. S. and Seal, S. K. and Unterberg, E. A. and Cianciosa, M. R. and Delgado-Aparicio, L. F. and Hirshman, S. P. and Lao, L. L.},
abstractNote = {The threshold for spontaneous symmetry breaking, which results in growth of m/n = 1/1 helical cores, in tokamaks is determined using VMEC. This model is based on a DIII-D hybrid discharge with helical core, and it predicts ITER (15MA scenario) to operate far in the helical core formation regime. Helical cores can only exist in tokamak discharges with monotonic but low, or reversed q-shear and qmin 1 in the core. The helical core is a saturated internal kink mode; its onset threshold is proportional to (dp/d)/B2t around q = 1. Below the threshold, applied 3-D fields can drive a helical core to finite size, as in DIIID. Above it, a random 3-D kick causes a bifurcation from axisymmetry and excites a spontaneous helical core. Helical cores occur frequently in C-Mod due to impurities; modeling shows the axisymmetric equilibrium becomes unstable at the end of the current ramp up due to the slow current penetration and a resultant reversed shear q-profile, which lowers the threshold. Lastly, a comparison of the helical core onset threshold for discharges from DIII-D, C-Mod and ITER confirms that while DIII-D is marginally stable, C-Mod and especially ITER are highly susceptible to helical core formation.},
doi = {10.1088/1741-4326/aaa33d},
journal = {Nuclear Fusion},
number = 3,
volume = 58,
place = {United States},
year = {Mon Jan 15 00:00:00 EST 2018},
month = {Mon Jan 15 00:00:00 EST 2018}
}
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Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record
https://doi.org/10.1088/1741-4326/aaa33d
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Cited by: 9 works
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Figures / Tables:

Figure 1 Figure 1: Time evolution of the local soft X-ray emission along the major radius at Z = 0 in shot 164661, obtained by tomographic inversion of measured, line-integrated soft-X-ray data.
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Works referenced in this record:

Self-Organized Stationary States of Tokamaks
journal, November 2015

Molybdenum emission from impurity-induced m = 1 snake-modes on the Alcator C-Mod tokamak
journal, October 2012

  • Delgado-Aparicio, L.; Bitter, M.; Granetz, R.
  • Review of Scientific Instruments, Vol. 83, Issue 10
  • DOI: 10.1063/1.4733731

Persistent density perturbations at rational- q surfaces following pellet injection in the Joint European Torus
journal, November 1987

Formation and Stability of Impurity “Snakes” in Tokamak Plasmas
journal, February 2013

Nonlinear evolution of ideal internal kink modes in tokamaks with nonmonotonic q profiles
journal, October 1990

  • Avinash, K.
  • Physics of Fluids B: Plasma Physics, Vol. 2, Issue 10
  • DOI: 10.1063/1.859503

Steepest-descent moment method for three-dimensional magnetohydrodynamic equilibria
journal, January 1983

Stability of ideal and resistive internal kink modes in toroidal geometry
journal, January 1987

  • Hastie, R. J.; Hender, T. C.; Carreras, B. A.
  • Physics of Fluids, Vol. 30, Issue 6
  • DOI: 10.1063/1.866242

Internal Kink Modes in Toroidal Plasmas with Circular Cross Sections
journal, December 1975

Nonlinear growth of the quasi‐interchange instability
journal, March 1989

  • Waelbroeck, F. L.
  • Physics of Fluids B: Plasma Physics, Vol. 1, Issue 3
  • DOI: 10.1063/1.859165

Tungsten as target material in fusion devices
journal, June 1996

Stationary high-performance discharges in the DIII-D tokamak
journal, April 2003

Impact of ideal MHD stability limits on high-beta hybrid operation
journal, November 2016

NBI fast ion confinement in the helical core of MAST hybrid-like plasmas
journal, May 2014

Role of a continuous MHD dynamo in the formation of 3D equilibria in fusion plasmas
journal, May 2017

Sawtooth oscillations
journal, January 1986

JET snake magnetohydrodynamic equilibria
journal, June 2011

Snake-like phenomena in Tore Supra following pellet injection
journal, April 1997

Reconstruction of current profile parameters and plasma shapes in tokamaks
journal, November 1985

V3FIT: a code for three-dimensional equilibrium reconstruction
journal, July 2009

Bifurcated helical core equilibrium states in tokamaks
journal, June 2013

Helical core reconstruction of a DIII-D hybrid scenario tokamak discharge
journal, May 2017

Connection between plasma response and resonant magnetic perturbation (RMP) edge localized mode (ELM) suppression in DIII-D
journal, September 2015

Use of reconstructed 3D VMEC equilibria to match effects of toroidally rotating discharges in DIII-D
journal, October 2016

Free boundary equilibrium in 3D tokamaks with toroidal rotation
journal, May 2015

Ideal saturated MHD helical structures in axisymmetric hybrid plasmas
journal, May 2014

Chapter 1: Overview and summary
journal, December 1999

  • Editors, ITER Physics Basis; Co-Chairs, ITER Physics Expert Group Chairs an; Unit, ITER Joint Central Team and Physics
  • Nuclear Fusion, Vol. 39, Issue 12
  • DOI: 10.1088/0029-5515/39/12/301

3D vacuum magnetic field modelling of the ITER ELM control coil during standard operating scenarios
journal, August 2013

Nonlinear magnetohydrodynamics
journal, January 1995

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    Works referencing / citing this record:

    Helical core formation and evolution during current ramp-up in the high-field tokamak Alcator C-Mod
    journal, February 2019

    • Wingen, A.; Wilcox, R. S.; Delgado-Aparicio, L. F.
    • Physics of Plasmas, Vol. 26, Issue 2
    • DOI: 10.1063/1.5083055

    Experimental observations of an n = 1 helical core accompanied by a saturated m / n = 2/1 tearing mode with low mode frequencies in JT-60U
    journal, October 2019

    • Bando, T.; Matsunaga, G.; Takechi, M.
    • Plasma Physics and Controlled Fusion, Vol. 61, Issue 11
    • DOI: 10.1088/1361-6587/ab4612

    Shear Alfvén wave continuum spectrum with bifurcated helical core equilibria
    journal, September 2019

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      Figures / Tables found in this record:

      Figure 1 (p. 4)figure
      Figure 2 (p. 5)figure
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      Figure 11 (p. 15)figure
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      Figure 14 (p. 17)figure
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