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Mulholland P, Aleynikova K, Faber BJ, Pueschel MJ, Proll JHE, Hegna CC, Terry PW, Nührenberg C. Enhanced Transport at High Plasma Pressure and Subthreshold Kinetic Ballooning Modes in Wendelstein 7-X. Phys Rev Lett 2023; 131:185101. [PMID: 37977609 DOI: 10.1103/physrevlett.131.185101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2023] [Revised: 08/18/2023] [Accepted: 09/19/2023] [Indexed: 11/19/2023]
Abstract
High-performance fusion plasmas, requiring high pressure β, are not well understood in stellarator-type experiments. Here, the effect of β on ion-temperature-gradient-driven (ITG) turbulence is studied in Wendelstein 7-X (W7-X), showing that subdominant kinetic ballooning modes (KBMs) are unstable well below the ideal MHD threshold and get strongly excited in the turbulence. By zonal-flow erosion, these subthreshold KBMs (stKBMs) affect ITG saturation and enable higher heat fluxes. Controlling stKBMs will be essential to allow W7-X and future stellarators to achieve maximum performance.
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Affiliation(s)
- P Mulholland
- Eindhoven University of Technology, 5600 MB Eindhoven, Netherlands
| | - K Aleynikova
- Max-Planck-Institut für Plasmaphysik, 17491 Greifswald, Germany
| | - B J Faber
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - M J Pueschel
- Eindhoven University of Technology, 5600 MB Eindhoven, Netherlands
- Dutch Institute for Fundamental Energy Research, 5612 AJ Eindhoven, Netherlands
- Department of Physics and Astronomy, Ruhr-Universität Bochum, D-44780 Bochum, Germany
| | - J H E Proll
- Eindhoven University of Technology, 5600 MB Eindhoven, Netherlands
| | - C C Hegna
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - P W Terry
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - C Nührenberg
- Max-Planck-Institut für Plasmaphysik, 17491 Greifswald, Germany
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Affiliation(s)
- J. Nührenberg
- IPP-Euratom Association Max-Planck-Institut für Plasmaphysik Garching Federal Republic of Germany
| | - W. Lotz
- IPP-Euratom Association Max-Planck-Institut für Plasmaphysik Garching Federal Republic of Germany
| | - P. Merkel
- IPP-Euratom Association Max-Planck-Institut für Plasmaphysik Garching Federal Republic of Germany
| | - C. Nührenberg
- IPP-Euratom Association Max-Planck-Institut für Plasmaphysik Garching Federal Republic of Germany
| | - U. Schwenn
- IPP-Euratom Association Max-Planck-Institut für Plasmaphysik Garching Federal Republic of Germany
| | - E. Strumberger
- IPP-Euratom Association Max-Planck-Institut für Plasmaphysik Garching Federal Republic of Germany
| | - T. Hayashi
- National Institute for Fusion Science Furocho Nagoya Japan
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Yamamoto S, Nagasaki K, Suzuki Y, Mizuuchi T, Okada H, Kobayashi S, Blackwell B, Kondo K, Motojima G, Nakajima N, Nakamura Y, Nührenberg C, Torii Y, Watanabe S, Sano F. Observation of Magnetohydrodynamic Instabilities in Heliotron J Plasmas. Fusion Science and Technology 2017. [DOI: 10.13182/fst07-a1290] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- S. Yamamoto
- Osaka University, Graduate School of Engineering, 2-1 Yamadaoka Suita 565-0871, Japan
| | - K. Nagasaki
- Kyoto University, Institute of Advanced Energy, Gokasho Uji 611-0011, Japan
| | - Y. Suzuki
- Kyoto University, Institute of Advanced Energy, Gokasho Uji 611-0011, Japan
| | - T. Mizuuchi
- Kyoto University, Institute of Advanced Energy, Gokasho Uji 611-0011, Japan
| | - H. Okada
- Kyoto University, Institute of Advanced Energy, Gokasho Uji 611-0011, Japan
| | - S. Kobayashi
- Kyoto University, Institute of Advanced Energy, Gokasho Uji 611-0011, Japan
| | - B. Blackwell
- The Australian National University, Research School of Physical Science and Engineering, Canberra, Australia
| | - K. Kondo
- Kyoto University, Graduate School of Energy Science, Gokasho Uji 611-0011, Japan
| | - G. Motojima
- Kyoto University, Graduate School of Energy Science, Gokasho Uji 611-0011, Japan
| | - N. Nakajima
- Kyoto University, Institute of Advanced Energy, Gokasho Uji 611-0011, Japan
| | - Y. Nakamura
- Kyoto University, Graduate School of Energy Science, Gokasho Uji 611-0011, Japan
| | - C. Nührenberg
- Max-Planck-Institut für Plasmaphysik, IPP-Euratom Association, Greifswald, Germany
| | - Y. Torii
- Kyoto University, Institute of Advanced Energy, Gokasho Uji 611-0011, Japan
| | - S. Watanabe
- Kyoto University, Graduate School of Energy Science, Gokasho Uji 611-0011, Japan
| | - F. Sano
- Kyoto University, Institute of Advanced Energy, Gokasho Uji 611-0011, Japan
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Weller A, Sakakibara S, Watanabe KY, Toi K, Geiger J, Zarnstorff MC, Hudson SR, Reiman A, Werner A, Nührenberg C, Ohdachi S, Suzuki Y, Yamada H. Significance of MHD Effects in Stellarator Confinement. Fusion Science and Technology 2017. [DOI: 10.13182/fst06-a1231] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Affiliation(s)
- A. Weller
- Max-Planck-Institut für Plasmaphysik, EURATOM-IPP Association, D-17491 Greifswald, Germany
| | - S. Sakakibara
- National Institute for Fusion Science, Toki 509-5292, Japan
| | - K. Y. Watanabe
- National Institute for Fusion Science, Toki 509-5292, Japan
| | - K. Toi
- National Institute for Fusion Science, Toki 509-5292, Japan
| | - J. Geiger
- Max-Planck-Institut für Plasmaphysik, EURATOM-IPP Association, D-17491 Greifswald, Germany
| | | | - S. R. Hudson
- Princeton Plasma Physics Laboratory, Princeton, NJ 08543
| | - A. Reiman
- Princeton Plasma Physics Laboratory, Princeton, NJ 08543
| | - A. Werner
- Max-Planck-Institut für Plasmaphysik, EURATOM-IPP Association, D-17491 Greifswald, Germany
| | - C. Nührenberg
- Max-Planck-Institut für Plasmaphysik, EURATOM-IPP Association, D-17491 Greifswald, Germany
| | - S. Ohdachi
- National Institute for Fusion Science, Toki 509-5292, Japan
| | - Y. Suzuki
- National Institute for Fusion Science, Toki 509-5292, Japan
| | - H. Yamada
- National Institute for Fusion Science, Toki 509-5292, Japan
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Dewar RL, Tatsuno T, Yoshida Z, Nührenberg C, McMillan BF. Statistical characterization of the interchange-instability spectrum of a separable ideal-magnetohydrodynamic model system. Phys Rev E Stat Nonlin Soft Matter Phys 2004; 70:066409. [PMID: 15697516 DOI: 10.1103/physreve.70.066409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2004] [Indexed: 05/24/2023]
Abstract
A Suydam-unstable circular cylinder of plasma with periodic boundary conditions in the axial direction is studied within the approximation of linearized ideal magnetohydrodynamics (MHD). The normal mode equations are completely separable, so both the toroidal Fourier harmonic index n and the poloidal index m are good quantum numbers. The full spectrum of eigenvalues in the range 1< or = m < or = m(max) is analyzed quantitatively, using asymptotics for large m, numerics for all m, and graphics for qualitative understanding. The density of eigenvalues scales like m(2)(max) as m(max) -->infinity . Because finite-m corrections scale as 1/ m(2)(max) , their inclusion is essential in order to obtain the correct statistics for the distribution of eigenvalues. Near the largest growth rate, only a single radial eigenmode contributes to the spectrum, so the eigenvalues there depend only on m and n as in a two-dimensional system. However, unlike the generic separable two-dimensional system, the statistics of the ideal-MHD spectrum departs somewhat from the Poisson distribution, even for arbitrarily large m(max) . This departure from Poissonian statistics may be understood qualitatively from the nature of the distribution of rational numbers in the rotational transform profile.
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Affiliation(s)
- R L Dewar
- Department of Theoretical Physics and Plasma Research Laboratory, Research School of Physical Sciences and Engineering, The Australian National University, ACT 0200, Australia.
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