1
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Ding S, Garofalo AM, Wang HQ, Weisberg DB, Li ZY, Jian X, Eldon D, Victor BS, Marinoni A, Hu QM, Carvalho IS, Odstrčil T, Wang L, Hyatt AW, Osborne TH, Gong XZ, Qian JP, Huang J, McClenaghan J, Holcomb CT, Hanson JM. A high-density and high-confinement tokamak plasma regime for fusion energy. Nature 2024; 629:555-560. [PMID: 38658758 PMCID: PMC11096097 DOI: 10.1038/s41586-024-07313-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2023] [Accepted: 03/14/2024] [Indexed: 04/26/2024]
Abstract
The tokamak approach, utilizing a toroidal magnetic field configuration to confine a hot plasma, is one of the most promising designs for developing reactors that can exploit nuclear fusion to generate electrical energy1,2. To reach the goal of an economical reactor, most tokamak reactor designs3-10 simultaneously require reaching a plasma line-averaged density above an empirical limit-the so-called Greenwald density11-and attaining an energy confinement quality better than the standard high-confinement mode12,13. However, such an operating regime has never been verified in experiments. In addition, a long-standing challenge in the high-confinement mode has been the compatibility between a high-performance core and avoiding large, transient edge perturbations that can cause very high heat loads on the plasma-facing-components in tokamaks. Here we report the demonstration of stable tokamak plasmas with a line-averaged density approximately 20% above the Greenwald density and an energy confinement quality of approximately 50% better than the standard high-confinement mode, which was realized by taking advantage of the enhanced suppression of turbulent transport granted by high density-gradients in the high-poloidal-beta scenario14,15. Furthermore, our experimental results show an integration of very low edge transient perturbations with the high normalized density and confinement core. The operating regime we report supports some critical requirements in many fusion reactor designs all over the world and opens a potential avenue to an operating point for producing economically attractive fusion energy.
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Affiliation(s)
- S Ding
- General Atomics, San Diego, CA, USA.
| | | | - H Q Wang
- General Atomics, San Diego, CA, USA
| | | | - Z Y Li
- General Atomics, San Diego, CA, USA
| | - X Jian
- General Atomics, San Diego, CA, USA
| | - D Eldon
- General Atomics, San Diego, CA, USA
| | - B S Victor
- Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - A Marinoni
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Q M Hu
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, NJ, USA
| | | | | | - L Wang
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | | | | | - X Z Gong
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | - J P Qian
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | - J Huang
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | | | - C T Holcomb
- Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - J M Hanson
- Department of Applied Mathematics and Applied Physics, Columbia University, New York, NY, USA
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2
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Wang L, Wang HQ, Ding S, Garofalo AM, Gong XZ, Eldon D, Guo HY, Leonard AW, Hyatt AW, Qian JP, Weisberg DB, McClenaghan J, Fenstermacher ME, Lasnier CJ, Watkins JG, Shafer MW, Xu GS, Huang J, Ren QL, Buttery RJ, Humphreys DA, Thomas DM, Zhang B, Liu JB. Integration of full divertor detachment with improved core confinement for tokamak fusion plasmas. Nat Commun 2021; 12:1365. [PMID: 33649306 PMCID: PMC7921092 DOI: 10.1038/s41467-021-21645-y] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2020] [Accepted: 01/29/2021] [Indexed: 11/24/2022] Open
Abstract
Divertor detachment offers a promising solution to the challenge of plasma-wall interactions for steady-state operation of fusion reactors. Here, we demonstrate the excellent compatibility of actively controlled full divertor detachment with a high-performance (βN ~ 3, H98 ~ 1.5) core plasma, using high-βp (poloidal beta, βp > 2) scenario characterized by a sustained core internal transport barrier (ITB) and a modest edge transport barrier (ETB) in DIII-D tokamak. The high-βp high-confinement scenario facilitates divertor detachment which, in turn, promotes the development of an even stronger ITB at large radius with a weaker ETB. This self-organized synergy between ITB and ETB, leads to a net gain in energy confinement, in contrast to the net confinement loss caused by divertor detachment in standard H-modes. These results show the potential of integrating excellent core plasma performance with an efficient divertor solution, an essential step towards steady-state operation of reactor-grade plasmas.
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Affiliation(s)
- L Wang
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | - H Q Wang
- General Atomics, San Diego, CA, USA.
| | - S Ding
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
- Oak Ridge Associated Universities, Oak Ridge, TN, USA
| | | | - X Z Gong
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | - D Eldon
- General Atomics, San Diego, CA, USA
| | - H Y Guo
- General Atomics, San Diego, CA, USA
| | | | | | - J P Qian
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | | | | | | | - C J Lasnier
- Lawrence Livermore National Laboratory, Livermore, CA, USA
| | - J G Watkins
- Sandia National Laboratories, Livermore, CA, USA
| | - M W Shafer
- Oak Ridge National Laboratory, Oak Ridge, TN, USA
| | - G S Xu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | - J Huang
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | - Q L Ren
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | | | | | | | - B Zhang
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
| | - J B Liu
- Institute of Plasma Physics, Chinese Academy of Sciences, Hefei, China
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3
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Jian X, Holland C, Candy J, Belli E, Chan V, Garofalo AM, Ding S. Role of Microtearing Turbulence in DIII-D High Bootstrap Current Fraction Plasmas. Phys Rev Lett 2019; 123:225002. [PMID: 31868395 DOI: 10.1103/physrevlett.123.225002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2019] [Revised: 10/03/2019] [Indexed: 06/10/2023]
Abstract
We report on the first direct comparisons of microtearing turbulence simulations to experimental measurements in a representative high bootstrap current fraction (f_{BS}) plasma. Previous studies of high f_{BS} plasmas carried out in DIII-D with large radius internal transport barriers (ITBs) have found that, while the ion energy transport is accurately reproduced by neoclassical theory, the electron transport remains anomalous and not well described by existing quasilinear transport models. A key feature of these plasmas is the large value of the normalized pressure gradient, which is shown to completely stabilize conventional drift-wave and kinetic ballooning mode instabilities in the ITB, but destabilizes the microtearing mode. Nonlinear gyrokinetic simulations of the ITB region performed with the cgyro code demonstrate that the microtearing modes are robustly unstable and capable of driving electron energy transport levels comparable to experimental levels for input parameters consistent with the experimental measurements. These simulations uniformly predict that the microtearing mode fluctuation and flux spectra extend to significantly shorter wavelengths than the range of linear instability, representing significantly different nonlinear dynamics and saturation mechanisms than conventional drift-wave turbulence, which is also consistent with the fundamental tearing nature of the instability. The predicted transport levels are found to be most sensitive to the magnetic shear, rather than the temperature gradients more typically identified as driving turbulent plasma transport.
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Affiliation(s)
- X Jian
- University of California, San Diego, La Jolla, California 92093-0417, USA
| | - C Holland
- University of California, San Diego, La Jolla, California 92093-0417, USA
| | - J Candy
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - E Belli
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - V Chan
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - A M Garofalo
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - S Ding
- Oak Ridge Associated Universities, Oak Ridge, Tennessee 37831, USA
- Institute of Plasma Physics, Chinese Academy of Sciences, P.O. Box 1126, Hefei, Anhui, 230031, China
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4
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Affiliation(s)
- A. M. Garofalo
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
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5
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Stambaugh RD, Chan VS, Garofalo AM, Sawan M, Humphreys DA, Lao LL, Leuer JA, Petrie TW, Prater R, Snyder PB, Smith JP, Wong CPC. Fusion Nuclear Science Facility Candidates. Fusion Science and Technology 2017. [DOI: 10.13182/fst59-279] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [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)
- R. D. Stambaugh
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - V. S. Chan
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - A. M. Garofalo
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - M. Sawan
- University of Wisconsin, Madison, Wisconsin
| | - D. A. Humphreys
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - L. L. Lao
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - J. A. Leuer
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - T. W. Petrie
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - R. Prater
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - P. B. Snyder
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - J. P. Smith
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - C. P. C. Wong
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
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6
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Chan VS, Stambaugh RD, Garofalo AM, Chu MS, Fisher RK, Greenfield CM, Humphreys DA, Lao LL, Leuer JA, Petrie TW, Prater R, Staebler GM, Snyder PB, John HES, Turnbull AD, Wong CPC, Van Zeeland MA. Physics Basis of a Fusion Development Facility Utilizing the Tokamak Approach. Fusion Science and Technology 2017. [DOI: 10.13182/fst10-a9269] [Citation(s) in RCA: 37] [Impact Index Per Article: 5.3] [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)
- V. S. Chan
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - R. D. Stambaugh
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - A. M. Garofalo
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - M. S. Chu
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - R. K. Fisher
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - C. M. Greenfield
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - D. A. Humphreys
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - L. L. Lao
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - J. A. Leuer
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - T. W. Petrie
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - R. Prater
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - G. M. Staebler
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - P. B. Snyder
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - H. E. St. John
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - A. D. Turnbull
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - C. P. C. Wong
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
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7
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Wong CPC, Chan VS, Garofalo AM, Leuer JA, Sawan ME, Smith JP, Stambaugh RD. Fusion Nuclear Science Facility - Advanced Tokamak Option. Fusion Science and Technology 2017. [DOI: 10.13182/fst60-449] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [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)
- C. P. C. Wong
- General Atomics, PO Box 85608, San Diego, California 92186-5608, USA
| | - V. S. Chan
- General Atomics, PO Box 85608, San Diego, California 92186-5608, USA
| | - A. M. Garofalo
- General Atomics, PO Box 85608, San Diego, California 92186-5608, USA
| | - J. A. Leuer
- General Atomics, PO Box 85608, San Diego, California 92186-5608, USA
| | - M. E. Sawan
- University of Wisconsin-Madison, 1500 Engineering Dr., Madison, Wisconsin 53706, USA
| | - J. P. Smith
- General Atomics, PO Box 85608, San Diego, California 92186-5608, USA
| | - R. D. Stambaugh
- General Atomics, PO Box 85608, San Diego, California 92186-5608, USA
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8
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Reimerdes H, Buttery RJ, Garofalo AM, In Y, La Haye RJ, Lanctot MJ, Okabayashi M, Park JK, Schaffer MJ, Strait EJ, Volpe FA. Error Field Tolerance and Error Field Correction Strategies and Their Applicability to ITER. Fusion Science and Technology 2017. [DOI: 10.13182/fst11-a11698] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [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)
| | | | | | - Y. In
- FAR-TECH, Inc. San Diego, California
| | | | | | - M. Okabayashi
- Princeton Plasma Physics Laboratory, Princeton, New Jersey
| | - J.-K. Park
- Princeton Plasma Physics Laboratory, Princeton, New Jersey
| | | | | | - F. A. Volpe
- University of Wisconsin–Madison, Madison, Wisconsin
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9
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Wong CPC, Chan VS, Garofalo AM, Stambaugh R, Sawan ME, Kurtz R, Merrill B. Fusion Nuclear Science Facility-AT: A Material and Component Testing Device. Fusion Science and Technology 2017. [DOI: 10.13182/fst12-a14148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [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)
- C. P. C. Wong
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - V. S. Chan
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - A. M. Garofalo
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - R. Stambaugh
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608
| | - M. E. Sawan
- University of Wisconsin-Madison, Madison, Wisconsin
| | - R. Kurtz
- Pacific Northwest National Laboratory, Richland, Washington
| | - B. Merrill
- Idaho National Laboratory, Idaho Falls, Idaho
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10
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Solomon WM, Snyder PB, Burrell KH, Fenstermacher ME, Garofalo AM, Grierson BA, Loarte A, McKee GR, Nazikian R, Osborne TH. Access to a new plasma edge state with high density and pressures using the quiescent H mode. Phys Rev Lett 2014; 113:135001. [PMID: 25302895 DOI: 10.1103/physrevlett.113.135001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Indexed: 06/04/2023]
Abstract
A path to a new high performance regime has been discovered in tokamaks that could improve the attractiveness of a fusion reactor. Experiments on DIII-D using a quiescent H-mode edge have navigated a valley of improved edge peeling-ballooning stability that opens up with strong plasma shaping at high density, leading to a doubling of the edge pressure over the standard H mode with edge localized modes at these parameters. The thermal energy confinement time increases as a result of both the increased pedestal height and improvements in the core transport and reduced low-k turbulence. Calculations of the pedestal height and width as a function of density using constraints imposed by peeling-ballooning and kinetic-ballooning theory are in quantitative agreement with the measurements.
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Affiliation(s)
- W M Solomon
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - P B Snyder
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - K H Burrell
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - M E Fenstermacher
- Lawrence Livermore National Laboratory, 7000 East Avenue, Livermore, California 94550, USA
| | - A M Garofalo
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - B A Grierson
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - A Loarte
- ITER Organization, Route de Vinon sur Verdon, CS 90 046, 13067 Saint Paul Lez Durance Cedex, France
| | - G R McKee
- University of Wisconsin-Madison, Madison, Wisconsin 53706, USA
| | - R Nazikian
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - T H Osborne
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
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11
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Cole AJ, Callen JD, Solomon WM, Garofalo AM, Hegna CC, Lanctot MJ, Reimerdes H. Observation of peak neoclassical toroidal viscous force in the DIII-D tokamak. Phys Rev Lett 2011; 106:225002. [PMID: 21702606 DOI: 10.1103/physrevlett.106.225002] [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: 07/21/2010] [Indexed: 05/31/2023]
Abstract
Observation of a theoretically predicted peak in the neoclassical toroidal viscosity (NTV) force as a function of toroidal plasma rotation rate Ω is reported. The NTV was generated by applying n=3 magnetic fields from internal coils to low Ω plasmas produced with nearly balanced neutral beam injection. Locally, the peak corresponds to a toroidal rotation rate Ω(0) where the radial electric field E(r) is near zero as determined by radial ion force balance.
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Affiliation(s)
- A J Cole
- University of Wisconsin, Madison, Wisconsin 53706-1609, USA
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12
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Reimerdes H, Berkery JW, Lanctot MJ, Garofalo AM, Hanson JM, In Y, Okabayashi M, Sabbagh SA, Strait EJ. Evidence for the importance of trapped particle resonances for resistive wall mode stability in high beta tokamak plasmas. Phys Rev Lett 2011; 106:215002. [PMID: 21699306 DOI: 10.1103/physrevlett.106.215002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2010] [Indexed: 05/31/2023]
Abstract
Active measurements of the plasma stability in tokamak plasmas reveal the importance of kinetic resonances for resistive wall mode stability. The rotation dependence of the magnetic plasma response to externally applied quasistatic n=1 magnetic fields clearly shows the signatures of an interaction between the resistive wall mode and the precession and bounce motions of trapped thermal ions, as predicted by a perturbative model of plasma stability including kinetic effects. The identification of the stabilization mechanism is an essential step towards quantitative predictions for the prospects of "passive" resistive wall mode stabilization, i.e., without the use of an "active" feedback system, in fusion-alpha heated plasmas.
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Affiliation(s)
- H Reimerdes
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027-6902, USA
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13
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Garofalo AM, Burrell KH, DeBoo JC, deGrassie JS, Jackson GL, Lanctot M, Reimerdes H, Schaffer MJ, Solomon WM, Strait EJ. Observation of plasma rotation driven by static nonaxisymmetric magnetic fields in a tokamak. Phys Rev Lett 2008; 101:195005. [PMID: 19113280 DOI: 10.1103/physrevlett.101.195005] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2008] [Indexed: 05/27/2023]
Abstract
We present the first evidence for the existence of a neoclassical toroidal rotation driven in a direction counter to the plasma current by nonaxisymmetric, nonresonant magnetic fields. At high beta and with large injected neutral beam momentum, the nonresonant field torque slows down the plasma toward the neoclassical "offset" rotation rate. With small injected neutral beam momentum, the toroidal rotation is accelerated toward the offset rotation, with resulting improvement in the global energy confinement time. The observed magnitude, direction, and radial profile of the offset rotation are consistent with neoclassical theory predictions.
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Affiliation(s)
- A M Garofalo
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
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14
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Reimerdes H, Garofalo AM, Jackson GL, Okabayashi M, Strait EJ, Chu MS, In Y, La Haye RJ, Lanctot MJ, Liu YQ, Navratil GA, Solomon WM, Takahashi H, Groebner RJ. Reduced critical rotation for resistive-wall mode stabilization in a near-axisymmetric configuration. Phys Rev Lett 2007; 98:055001. [PMID: 17358868 DOI: 10.1103/physrevlett.98.055001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2006] [Indexed: 05/14/2023]
Abstract
Recent DIII-D experiments with reduced neutral beam torque and minimum nonaxisymmetric perturbations of the magnetic field show a significant reduction of the toroidal plasma rotation required for the stabilization of the resistive-wall mode (RWM) below the threshold values observed in experiments that apply nonaxisymmetric magnetic fields to slow the plasma rotation. A toroidal rotation frequency of less than 10 krad/s at the q=2 surface (measured with charge exchange recombination spectroscopy using C VI) corresponding to 0.3% of the inverse of the toroidal Alfvén time is sufficient to sustain the plasma pressure above the ideal MHD no-wall stability limit. The low-rotation threshold is found to be consistent with predictions by a kinetic model of RWM damping.
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Affiliation(s)
- H Reimerdes
- Columbia University, New York, New York 10027, USA
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15
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Reimerdes H, Chu MS, Garofalo AM, Jackson GL, La Haye RJ, Navratil GA, Okabayashi M, Scoville JT, Strait EJ. Measurement of the resistive-wall-mode stability in a rotating plasma using active MHD spectroscopy. Phys Rev Lett 2004; 93:135002. [PMID: 15524728 DOI: 10.1103/physrevlett.93.135002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/17/2004] [Indexed: 05/24/2023]
Abstract
The stability of the resistive-wall mode (RWM) in DIII-D plasmas above the conventional pressure limit, where toroidal plasma rotation in the order of a few percent of the Alfve n velocity is sufficient to stabilize the n=1 RWM, has been probed using the technique of active MHD spectroscopy at frequencies of a few Hertz. The measured frequency spectrum of the plasma response to externally applied rotating resonant magnetic fields is well described by a single-mode approach and provides an absolute measurement of the damping rate and the natural mode rotation frequency of the stable RWM.
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Affiliation(s)
- H Reimerdes
- Columbia University, New York, New York, USA
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16
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Garofalo AM, Strait EJ, Johnson LC, La Haye RJ, Lazarus EA, Navratil GA, Okabayashi M, Scoville JT, Taylor TS, Turnbull AD. Sustained stabilization of the resistive-wall mode by plasma rotation in the DIII-D tokamak. Phys Rev Lett 2002; 89:235001. [PMID: 12485014 DOI: 10.1103/physrevlett.89.235001] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2001] [Indexed: 05/24/2023]
Abstract
Values of the normalized plasma pressure up to twice the free-boundary stability limit predicted by ideal magnetohydrodynamic (MHD) theory have been sustained in the DIII-D tokamak. Long-wavelength modes are stabilized by the resistive wall and rapid plasma toroidal rotation. High rotation speed is maintained by minimization of nonaxisymmetric magnetic fields, overcoming a long-standing impediment [E. J. Strait, Phys. Rev. Lett. 74, 2483 (1995)]]. The ideal-MHD pressure limit calculated with an ideal wall is observed as the operational limit to the normalized plasma pressure.
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Affiliation(s)
- A M Garofalo
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA.
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Garofalo AM. Telecommunications provides key to cost-effective security. Hosp Top 1983; 61:16-7. [PMID: 10263264 DOI: 10.1080/00185868.1983.9948329] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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