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:
-
- National Fusion Research Institute, Daejeon (Republic of Korea)
- Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- ITER Organization, St. Paul Lez Durance (France)
- 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}
}
Web of Science
Works referenced in this record:
Error Field Amplification and Rotation Damping in Tokamak Plasmas
journal, May 2001
- Boozer, Allen H.
- Physical Review Letters, Vol. 86, Issue 22
Stability and control of resistive wall modes in high beta, low rotation DIII-D plasmas
journal, August 2007
- Garofalo, A. M.; Jackson, G. L.; La Haye, R. J.
- Nuclear Fusion, Vol. 47, Issue 9
Suppression of Large Edge-Localized Modes in High-Confinement DIII-D Plasmas with a Stochastic Magnetic Boundary
journal, June 2004
- Evans, T. E.; Moyer, R. A.; Thomas, P. R.
- Physical Review Letters, Vol. 92, Issue 23
Chapter 3: MHD stability, operational limits and disruptions
journal, June 2007
- Hender, T. C.; Wesley, J. C.; Bialek, J.
- Nuclear Fusion, Vol. 47, Issue 6
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
Control of Nonaxisymmetric Magnetic Field Perturbations in Tokamaks
journal, April 2011
- Boozer, Allen H.
- Fusion Science and Technology, Vol. 59, Issue 3
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
Control of Asymmetric Magnetic Perturbations in Tokamaks
journal, November 2007
- Park, Jong-kyu; Schaffer, Michael J.; Menard, Jonathan E.
- Physical Review Letters, Vol. 99, Issue 19
Tokamak Operation with Safety Factor via Control of MHD Stability
journal, July 2014
- Piovesan, P.; Hanson, J. M.; Martin, P.
- Physical Review Letters, Vol. 113, Issue 4
Effects of neoclassical toroidal viscosity induced by the intrinsic error fields and toroidal field ripple on the toroidal rotation in tokamaks
journal, August 2016
- Lee, H. H.; Seol, J.; Ko, W. H.
- Physics of Plasmas, Vol. 23, Issue 8
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
Nonlinear Interaction of Edge-Localized Modes and Turbulent Eddies in Toroidal Plasma under Magnetic Perturbation
journal, August 2016
- Lee, Jaehyun; Yun, Gunsu S.; Choi, Minjun J.
- Physical Review Letters, Vol. 117, Issue 7
Design features of the KSTAR in-vessel control coils
journal, June 2009
- Kim, H. K.; Yang, H. L.; Kim, G. H.
- Fusion Engineering and Design, Vol. 84, Issue 2-6
Versatile controllability of non-axisymmetric magnetic perturbations in KSTAR experiments
journal, October 2016
- Han, Hyunsun; Jeon, Y. M.; Hahn, S. H.
- Fusion Engineering and Design, Vol. 108
Three-Dimensional Drift Kinetic Response of High- Plasmas in the DIII-D Tokamak
journal, April 2015
- Wang, Z. R.; Lanctot, M. J.; Liu, Y. Q.
- Physical Review Letters, Vol. 114, Issue 14
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
Suppression of Edge Localized Modes in High-Confinement KSTAR Plasmas by Nonaxisymmetric Magnetic Perturbations
journal, July 2012
- Jeon, Y. M.; Park, J. -K.; Yoon, S. W.
- Physical Review Letters, Vol. 109, Issue 3
L–H transition studies on DIII-D to determine H-mode access for operational scenarios in ITER
journal, August 2011
- Gohil, P.; Evans, T. E.; Fenstermacher, M. E.
- Nuclear Fusion, Vol. 51, Issue 10
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
ELMs and constraints on the H-mode pedestal: peeling–ballooning stability calculation and comparison with experiment
journal, January 2004
- Snyder, P. B.; Wilson, H. R.; Ferron, J. R.
- Nuclear Fusion, Vol. 44, Issue 2
Works referencing / citing this record:
3D field phase-space control in tokamak plasmas
journal, September 2018
- Park, Jong-Kyu; Jeon, YoungMu; In, Yongkyoon
- Nature Physics, Vol. 14, Issue 12
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