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Title: Enhanced understanding of non-axisymmetric intrinsic and controlled field impacts in tokamaks

Abstract

Here, an extensive study of intrinsic and controlled non-axisymmetric field (δB) impacts in KSTAR has enhanced the understanding about non-axisymmetric field physics and its implications, in particular, on resonant magnetic perturbation (RMP) physics and power threshold (P th) for L–H transition. The n=1 intrinsic non-axisymmetric field in KSTAR was measured to remain as low as δB/B 0 ~ 4×10–5 even at high-beta plasmas (β N ~ 2), which corresponds to approximately 20% below the targeted ITER tolerance level. As for the RMP edge-localized-modes (ELM) control, robust n=1 RMP ELM-crash-suppression has been not only sustained for more than ~90 τ E, but also confirmed to be compatible with rotating RMP. An optimal window of radial position of lower X-point (i.e. R x = $$1.44\pm 0.02\,$$ m) proved to be quite critical to reach full n=1 RMP-driven ELM-crash-suppression, while a constraint of the safety factor could be relaxed (q 95 = 5 $$\pm $$ 0.25). A more encouraging finding was that even when R x cannot be positioned in the optimal window, another systematic scan in the vicinity of the previously optimal R x allows for a new optimal window with relatively small variations of plasma parameters. Also, we have addressed the importance of optimal phasing (i.e. toroidal phase difference between adjacent rows) for n=1 RMP-driven ELM control, consistent with an ideal plasma response modeling which could predict phasing-dependent ELM suppression windows. In support of ITER RMP study, intentionally misaligned RMPs have been found to be quite effective during ELM-mitigation stage in lowering the peaks of divertor heat flux, as well as in broadening the 'wet' areas. Besides, a systematic survey of P th dependence on non-axisymmetric field has revealed the potential limit of the merit of low intrinsic non-axisymmetry. Considering that the ITER RMP coils are composed of 3-rows, just like in KSTAR, further 3D physics study in KSTAR is expected to help us minimize the uncertainties of the ITER RMP coils, as well as establish an optimal 3D configuration for ITER and future reactors.

Authors:
 [1];  [2];  [1];  [1];  [1];  [3];  [4];  [1];  [1];  [1];  [1];  [1];  [5]
  1. National Fusion Research Institute, Daejeon (Republic of Korea)
  2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
  3. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  4. ITER Organization, St. Paul Lez Durance (France)
  5. National Fusion Research Institute, Daejeon (Republic of Korea); Ulsan National Institute of Science and Technology, Ulsan (Republic of Korea)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE
Contributing Org.:
3D Physics Task Force in KSTAR
OSTI Identifier:
1434245
Grant/Contract Number:  
AC02-09CH11466
Resource Type:
Accepted Manuscript
Journal Name:
Nuclear Fusion
Additional Journal Information:
Journal Volume: 57; Journal Issue: 11; Journal ID: ISSN 0029-5515
Publisher:
IOP Science
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; RMP; ELM control; power threshold; 3D physics; ELM suppression; plasma response

Citation Formats

In, Y., Park, J. -K., Jeon, Y. M., Kim, J., Park, G. Y., Ahn, J. -W., Loarte, A., Ko, W. H., Lee, H. H., Yoo, J. W., Juhn, J. W., Yoon, S. W., and Park, H. Enhanced understanding of non-axisymmetric intrinsic and controlled field impacts in tokamaks. United States: N. p., 2017. Web. doi:10.1088/1741-4326/aa791c.
In, Y., Park, J. -K., Jeon, Y. M., Kim, J., Park, G. Y., Ahn, J. -W., Loarte, A., Ko, W. H., Lee, H. H., Yoo, J. W., Juhn, J. W., Yoon, S. W., & Park, H. Enhanced understanding of non-axisymmetric intrinsic and controlled field impacts in tokamaks. United States. https://doi.org/10.1088/1741-4326/aa791c
In, Y., Park, J. -K., Jeon, Y. M., Kim, J., Park, G. Y., Ahn, J. -W., Loarte, A., Ko, W. H., Lee, H. H., Yoo, J. W., Juhn, J. W., Yoon, S. W., and Park, H. Thu . "Enhanced understanding of non-axisymmetric intrinsic and controlled field impacts in tokamaks". United States. https://doi.org/10.1088/1741-4326/aa791c. https://www.osti.gov/servlets/purl/1434245.
@article{osti_1434245,
title = {Enhanced understanding of non-axisymmetric intrinsic and controlled field impacts in tokamaks},
author = {In, Y. and Park, J. -K. and Jeon, Y. M. and Kim, J. and Park, G. Y. and Ahn, J. -W. and Loarte, A. and Ko, W. H. and Lee, H. H. and Yoo, J. W. and Juhn, J. W. and Yoon, S. W. and Park, H.},
abstractNote = {Here, an extensive study of intrinsic and controlled non-axisymmetric field (δB) impacts in KSTAR has enhanced the understanding about non-axisymmetric field physics and its implications, in particular, on resonant magnetic perturbation (RMP) physics and power threshold (P th) for L–H transition. The n=1 intrinsic non-axisymmetric field in KSTAR was measured to remain as low as δB/B 0 ~ 4×10–5 even at high-beta plasmas (β N ~ 2), which corresponds to approximately 20% below the targeted ITER tolerance level. As for the RMP edge-localized-modes (ELM) control, robust n=1 RMP ELM-crash-suppression has been not only sustained for more than ~90 τ E, but also confirmed to be compatible with rotating RMP. An optimal window of radial position of lower X-point (i.e. R x = $1.44\pm 0.02\,$ m) proved to be quite critical to reach full n=1 RMP-driven ELM-crash-suppression, while a constraint of the safety factor could be relaxed (q 95 = 5 $\pm $ 0.25). A more encouraging finding was that even when R x cannot be positioned in the optimal window, another systematic scan in the vicinity of the previously optimal R x allows for a new optimal window with relatively small variations of plasma parameters. Also, we have addressed the importance of optimal phasing (i.e. toroidal phase difference between adjacent rows) for n=1 RMP-driven ELM control, consistent with an ideal plasma response modeling which could predict phasing-dependent ELM suppression windows. In support of ITER RMP study, intentionally misaligned RMPs have been found to be quite effective during ELM-mitigation stage in lowering the peaks of divertor heat flux, as well as in broadening the 'wet' areas. Besides, a systematic survey of P th dependence on non-axisymmetric field has revealed the potential limit of the merit of low intrinsic non-axisymmetry. Considering that the ITER RMP coils are composed of 3-rows, just like in KSTAR, further 3D physics study in KSTAR is expected to help us minimize the uncertainties of the ITER RMP coils, as well as establish an optimal 3D configuration for ITER and future reactors.},
doi = {10.1088/1741-4326/aa791c},
journal = {Nuclear Fusion},
number = 11,
volume = 57,
place = {United States},
year = {Thu Aug 24 00:00:00 EDT 2017},
month = {Thu Aug 24 00:00:00 EDT 2017}
}

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Works referenced in this record:

Error Field Amplification and Rotation Damping in Tokamak Plasmas
journal, May 2001


Stability and control of resistive wall modes in high beta, low rotation DIII-D plasmas
journal, August 2007


Suppression of Large Edge-Localized Modes in High-Confinement DIII-D Plasmas with a Stochastic Magnetic Boundary
journal, June 2004


Chapter 3: MHD stability, operational limits and disruptions
journal, June 2007


Chapter 2: Plasma confinement and transport
journal, June 2007

  • Physics), E. J. Doyle (Chair Transport; Modelling), W. A. Houlberg (Chair Confinement Da; Edge), Y. Kamada (Chair Pedestal and
  • Nuclear Fusion, Vol. 47, Issue 6
  • DOI: 10.1088/0029-5515/47/6/S02

Control of Nonaxisymmetric Magnetic Field Perturbations in Tokamaks
journal, April 2011


The limits and challenges of error field correction for ITER
journal, May 2012

  • Buttery, R. J.; Boozer, A. H.; Liu, Y. Q.
  • Physics of Plasmas, Vol. 19, Issue 5
  • DOI: 10.1063/1.3694655

Control of Asymmetric Magnetic Perturbations in Tokamaks
journal, November 2007


Tokamak Operation with Safety Factor q 95 < 2 via Control of MHD Stability
journal, July 2014


Two-dimensional imaging of edge-localized modes in KSTAR plasmas unperturbed and perturbed by n=1 external magnetic fields
journal, May 2012

  • Yun, G. S.; Lee, W.; Choi, M. J.
  • Physics of Plasmas, Vol. 19, Issue 5
  • DOI: 10.1063/1.3694842

Nonlinear Interaction of Edge-Localized Modes and Turbulent Eddies in Toroidal Plasma under n = 1 Magnetic Perturbation
journal, August 2016


Design features of the KSTAR in-vessel control coils
journal, June 2009


Versatile controllability of non-axisymmetric magnetic perturbations in KSTAR experiments
journal, October 2016


Three-Dimensional Drift Kinetic Response of High- β Plasmas in the DIII-D Tokamak
journal, April 2015


Computation of three-dimensional tokamak and spherical torus equilibria
journal, May 2007

  • Park, Jong-kyu; Boozer, Allen H.; Glasser, Alan H.
  • Physics of Plasmas, Vol. 14, Issue 5
  • DOI: 10.1063/1.2732170

Suppression of Edge Localized Modes in High-Confinement KSTAR Plasmas by Nonaxisymmetric Magnetic Perturbations
journal, July 2012


L–H transition studies on DIII-D to determine H-mode access for operational scenarios in ITER
journal, August 2011


Power requirement for accessing the H-mode in ITER
journal, July 2008

  • Martin, Y. R.; Takizuka, T.; Group, the ITPA CDBM H-mode Threshold Data
  • Journal of Physics: Conference Series, Vol. 123
  • DOI: 10.1088/1742-6596/123/1/012033

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


Works referencing / citing this record:

3D field phase-space control in tokamak plasmas
journal, September 2018


Enhanced fast ion prompt loss due to resonant magnetic perturbations in KSTAR
journal, December 2018

  • Kim, Kimin; Jhang, Hogun; Kim, Junghee
  • Physics of Plasmas, Vol. 25, Issue 12
  • DOI: 10.1063/1.5054178