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Brunetti D, Graves JP, Ham CJ, Saarelma S. Occam's razor on the mechanism of resistive-wall-mode-induced β limits in diverted tokamaks. Phys Rev E 2023; 107:055203. [PMID: 37328974 DOI: 10.1103/physreve.107.055203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 04/21/2023] [Indexed: 06/18/2023]
Abstract
External kink modes, believed to be the drive of the β-limiting resistive wall mode, are strongly stabilized by the presence of a separatrix. We thus propose a novel mechanism explaining the appearance of long-wavelength global instabilities in free boundary high-β diverted tokamaks, retrieving the experimental observables within a physical framework dramatically simpler than most of the models employed for the description of such phenomena. It is shown that the magnetohydrodynamic stability is worsened by the synergy of β and plasma resistivity, with wall effects significantly screened in an ideal, i.e., with vanishing resistivity, plasma with separatrix. Stability can be improved by toroidal flows, depending on the proximity to the resistive marginal boundary. The analysis is performed in tokamak toroidal geometry, and includes averaged curvature and essential separatrix effects.
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Affiliation(s)
- D Brunetti
- UKAEA-CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB, United Kingdom
| | - J P Graves
- École Polytechnique Fédérale de Lausanne (EPFL), Swiss Plasma Center (SPC), CH-1015 Lausanne, Switzerland
- York Plasma Institute, Department of Physics, University of York, York, Heslington YO10 5DD, United Kingdom
| | - C J Ham
- UKAEA-CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB, United Kingdom
| | - S Saarelma
- UKAEA-CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB, United Kingdom
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2
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Zhu P, Li L, Fang Y, He Y, Wang S, Han R, Liu Y, Wang X, Zhang Y, Zhang X, Yu Q, Hu L, Wang H, Sun Y, Wei L, Tang W, Liu T, Wang Z, Yan X, Huang W, Hou Y, Ji X, Zeng S, Abdullah Z, Chen Z, Zeng L, Li H, Chen Z, Wang Z, Rao B, Zhang M, Ding Y, Pan Y. MHD Analysis on the Physics Design of CFETR Baseline Scenarios. JOURNAL OF FUSION ENERGY 2022. [DOI: 10.1007/s10894-022-00323-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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3
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Chrystal C, Haskey SR, Burrell KH, Grierson BA, Collins CS. Charge exchange recombination spectroscopy measurements of DIII-D poloidal rotation with poloidal asymmetry in angular rotation. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:043518. [PMID: 34243419 DOI: 10.1063/5.0043087] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Accepted: 03/19/2021] [Indexed: 06/13/2023]
Abstract
Sixteen new tangential views for the charge exchange recombination (CER) spectroscopy diagnostic at DIII-D were installed in 2019 on the high-field side (HFS) of the tokamak with the main goal being the measurement of main-ion (deuterium) poloidal rotation. Eight of the new views are connected to spectrometers, which view the main-ion spectrum, adding main-ion measurements where there were previously none, and another eight new views increased the spatial resolution of existing impurity (carbon) measurements on the HFS. When combined with the existing low-field side measurements, measurements at two locations on flux surfaces out to a normalized minor radius of ≈0.6 are possible. The new tangential views have been used to measure the deuterium poloidal rotation directly for the first time using the Poloidal Asymmetry in Angular Rotation (PAAR) method. These new measurements enable further testing of the validity of neoclassical poloidal rotation predictions. Separate measurements of the radial electric field can be made for an impurity ion and the main-ion by combining the PAAR measurements with additional CER measurements of toroidal rotation, temperature, and density. These independent measurements of the radial electric field agree reasonably well.
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Affiliation(s)
- C Chrystal
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - S R Haskey
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451, USA
| | - K H Burrell
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - B A Grierson
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543-0451, USA
| | - C S Collins
- Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, Tennessee 37831-6169, USA
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4
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Menard JE. Compact steady-state tokamak performance dependence on magnet and core physics limits. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2019; 377:20170440. [PMID: 30967044 PMCID: PMC6365855 DOI: 10.1098/rsta.2017.0440] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Accepted: 07/02/2018] [Indexed: 06/09/2023]
Abstract
Compact tokamak fusion reactors using advanced high-temperature superconducting magnets for the toroidal field coils have received considerable recent attention due to the promise of more compact devices and more economical fusion energy development. Facilities with combined fusion nuclear science and Pilot Plant missions to provide both the nuclear environment needed to develop fusion materials and components while also potentially achieving sufficient fusion performance to generate modest net electrical power are considered. The performance of the tokamak fusion system is assessed using a range of core physics and toroidal field magnet performance constraints to better understand which parameters most strongly influence the achievable fusion performance. This article is part of a discussion meeting issue 'Fusion energy using tokamaks: can development be accelerated?'.
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5
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Goumiri IR, Rowley CW, Sabbagh SA, Gates DA, Boyer MD, Gerhardt SP, Kolemen E, Menard JE. Simultaneous feedback control of plasma rotation and stored energy on NSTX-U using neoclassical toroidal viscosity and neutral beam injection. PHYSICS OF PLASMAS 2017; 24:056101. [PMID: 28435207 PMCID: PMC5375958 DOI: 10.1063/1.4976853] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Accepted: 11/21/2016] [Indexed: 06/07/2023]
Abstract
A model-based feedback system is presented enabling the simultaneous control of the stored energy through βn and the toroidal rotation profile of the plasma in National Spherical Torus eXperiment Upgrade device. Actuation is obtained using the momentum from six injected neutral beams and the neoclassical toroidal viscosity generated by applying three-dimensional magnetic fields. Based on a model of the momentum diffusion and torque balance, a feedback controller is designed and tested in closed-loop simulations using TRANSP, a time dependent transport analysis code, in predictive mode. Promising results for the ongoing experimental implementation of controllers are obtained.
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Affiliation(s)
- I R Goumiri
- Department of Physics, University of Wisconsin, Madison, Wisconsin 53706, USA
| | - C W Rowley
- Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - S A Sabbagh
- Department of Applied Physics, Columbia University, New York, New York 10027, USA
| | - D A Gates
- Princeton Plasma Physics Laboratory, Princeton, New Jersrey 08544, USA
| | - M D Boyer
- Princeton Plasma Physics Laboratory, Princeton, New Jersrey 08544, USA
| | - S P Gerhardt
- Princeton Plasma Physics Laboratory, Princeton, New Jersrey 08544, USA
| | - E Kolemen
- Princeton Plasma Physics Laboratory, Princeton, New Jersrey 08544, USA
| | - J E Menard
- Princeton Plasma Physics Laboratory, Princeton, New Jersrey 08544, USA
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6
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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] [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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7
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Grierson BA, Wang WX, Ethier S, Staebler GM, Battaglia DJ, Boedo JA, deGrassie JS, Solomon WM. Main-Ion Intrinsic Toroidal Rotation Profile Driven by Residual Stress Torque from Ion Temperature Gradient Turbulence in the DIII-D Tokamak. PHYSICAL REVIEW LETTERS 2017; 118:015002. [PMID: 28106437 DOI: 10.1103/physrevlett.118.015002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2016] [Indexed: 06/06/2023]
Abstract
Intrinsic toroidal rotation of the deuterium main ions in the core of the DIII-D tokamak is observed to transition from flat to hollow, forming an off-axis peak, above a threshold level of direct electron heating. Nonlinear gyrokinetic simulations show that the residual stress associated with electrostatic ion temperature gradient turbulence possesses the correct radial location and stress structure to cause the observed hollow rotation profile. Residual stress momentum flux in the gyrokinetic simulations is balanced by turbulent momentum diffusion, with negligible contributions from turbulent pinch. The prediction of the velocity profile by integrating the momentum balance equation produces a rotation profile that qualitatively and quantitatively agrees with the measured main-ion profile, demonstrating that fluctuation-induced residual stress can drive the observed intrinsic velocity profile.
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Affiliation(s)
- B A Grierson
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - W X Wang
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - S Ethier
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - G M Staebler
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - D J Battaglia
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - J A Boedo
- Center for Energy Research, University of California San Diego, 9500 Gilman Drive, La Jolla, California 92093-0417, USA
| | - J S deGrassie
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
| | - W M Solomon
- General Atomics, P.O. Box 85608, San Diego, California 92186-5608, USA
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8
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Shiraishi J, Miyato N, Matsunaga G. Flow-Induced New Channels of Energy Exchange in Multi-Scale Plasma Dynamics - Revisiting Perturbative Hybrid Kinetic-MHD Theory. Sci Rep 2016; 6:25644. [PMID: 27160346 PMCID: PMC4861913 DOI: 10.1038/srep25644] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 04/19/2016] [Indexed: 11/25/2022] Open
Abstract
It is found that new channels of energy exchange between macro- and microscopic dynamics exist in plasmas. They are induced by macroscopic plasma flow. This finding is based on the kinetic-magnetohydrodynamic (MHD) theory, which analyses interaction between macroscopic (MHD-scale) motion and microscopic (particle-scale) dynamics. The kinetic-MHD theory is extended to include effects of macroscopic plasma flow self-consistently. The extension is realised by generalising an energy exchange term due to wave-particle resonance, denoted by δ WK. The first extension is generalisation of the particle’s Lagrangian, and the second one stems from modification to the particle distribution function due to flow. These extensions lead to a generalised expression of δ WK, which affects the MHD stability of plasmas.
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Affiliation(s)
- Junya Shiraishi
- Japan Atomic Energy Agency, 801-1 Mukoyama, Naka, Ibaraki 311-0193, Japan
| | - Naoaki Miyato
- Japan Atomic Energy Agency, 2-166 Omotedate, Rokkasho, Aomori 039-3212, Japan
| | - Go Matsunaga
- Japan Atomic Energy Agency, 801-1 Mukoyama, Naka, Ibaraki 311-0193, Japan
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9
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Aiba N, Hirota M. Excitation of flow-stabilized resistive wall mode by coupling with stable eigenmodes in tokamaks. PHYSICAL REVIEW LETTERS 2015; 114:065001. [PMID: 25723224 DOI: 10.1103/physrevlett.114.065001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2014] [Indexed: 06/04/2023]
Abstract
In a rotating toroidal plasma surrounded by a resistive wall, it is shown that linear MHD instabilities can be excited by couplings between the resistive wall mode (RWM) and stable ideal MHD modes. In particular, it is shown that the RWM can couple not only with stable external kink modes but also with Alfvén eigenmodes that are ordinarily in the stable continuum of a toroidal plasma. The RWM growth rate is shown to peak whenever the Doppler shift caused by the plasma rotation cancels the frequency of an ideal MHD mode, so that the mode appears to have zero frequency in the laboratory frame. At these values of the rotation frequency, the RWM can overcome the stabilizing effects of plasma rotation, continuum damping, and ion Landau damping.
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Affiliation(s)
- Nobuyuki Aiba
- Japan Atomic Energy Agency, 2-166, Omotedate, Rokkasho, Aomori 039-3212, Japan
| | - Makoto Hirota
- Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai, Miyagi 980-8577, Japan
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10
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Menard JE, Wang Z, Liu Y, Bell RE, Kaye SM, Park JK, Tritz K. Rotation and kinetic modifications of the tokamak ideal-wall pressure limit. PHYSICAL REVIEW LETTERS 2014; 113:255002. [PMID: 25554890 DOI: 10.1103/physrevlett.113.255002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Indexed: 06/04/2023]
Abstract
The impact of toroidal rotation, energetic ions, and drift-kinetic effects on the tokamak ideal wall mode stability limit is considered theoretically and compared to experiment for the first time. It is shown that high toroidal rotation can be an important destabilizing mechanism primarily through the angular velocity shear; non-Maxwellian fast ions can also be destabilizing, and drift-kinetic damping can potentially offset these destabilization mechanisms. These results are obtained using the unique parameter regime accessible in the spherical torus NSTX of high toroidal rotation speed relative to the thermal and Alfvén speeds and high kinetic pressure relative to the magnetic pressure. Inclusion of rotation and kinetic effects significantly improves agreement between measured and predicted ideal stability characteristics and may provide new insight into tearing mode triggering.
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Affiliation(s)
- J E Menard
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - Z Wang
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - Y Liu
- Culham Centre for Fusion Energy, Culham Science Centre, Abingdon OX14 3DB, United Kingdom
| | - R E Bell
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - S M Kaye
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - J-K Park
- Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543, USA
| | - K Tritz
- Johns Hopkins University, Baltimore, Maryland 21218, USA
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11
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Park JK, Jeon YM, Menard JE, Ko WH, Lee SG, Bae YS, Joung M, You KI, Lee KD, Logan N, Kim K, Ko JS, Yoon SW, Hahn SH, Kim JH, Kim WC, Oh YK, Kwak JG. Rotational resonance of nonaxisymmetric magnetic braking in the KSTAR tokamak. PHYSICAL REVIEW LETTERS 2013; 111:095002. [PMID: 24033042 DOI: 10.1103/physrevlett.111.095002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Indexed: 06/02/2023]
Abstract
One of the important rotational resonances in nonaxisymmetric neoclassical transport has been experimentally validated in the KSTAR tokamak by applying highly nonresonant n=1 magnetic perturbations to rapidly rotating plasmas. These so-called bounce-harmonic resonances are expected to occur in the presence of magnetic braking perturbations when the toroidal rotation is fast enough to resonate with periodic parallel motions of trapped particles. The predicted and observed resonant peak along with the toroidal rotation implies that the toroidal rotation in tokamaks can be controlled naturally in favorable conditions to stability, using nonaxisymmetric magnetic perturbations.
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Affiliation(s)
- J-K Park
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
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12
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Podestà M, Bell RE. A real-time velocity diagnostic for NSTX. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2012; 83:033503. [PMID: 22462918 DOI: 10.1063/1.3692752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
A new system for fast measurements of the plasma toroidal velocity has been installed on the National Spherical Torus Experiment, NSTX [M. Ono et al., Nucl. Fusion 40, 557 (2000)]. The diagnostic, based on active charge-exchange recombination spectroscopy, can measure at up to six radial locations with maximum sampling rate of 5 kHz. The system is interfaced in real time with the NSTX plasma control system, in order to feed back on plasma velocity by means of actuators such as neutral beams and external coils. The paper describes the design criteria and implementation of the diagnostic. Examples from the initial tests of the system during neon glows are also discussed.
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Affiliation(s)
- M Podestà
- Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
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13
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Hao GZ, Wang AK, Liu YQ, Qiu XM. Effect of trapped energetic particles on the resistive wall mode. PHYSICAL REVIEW LETTERS 2011; 107:015001. [PMID: 21797547 DOI: 10.1103/physrevlett.107.015001] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2011] [Indexed: 05/31/2023]
Abstract
A stability analysis for the resistive wall mode is studied in the presence of trapped energetic particles (EPs). When the EPs' beta exceeds a critical value, a fishbonelike bursting mode (FLM) with an external kink eigenstructure can exist. This offers the first analytic interpretation of the experimental observations [Phys. Rev. Lett. 103, 045001 (2009)]. The mode-particle resonances for the FLM and the q=1 fishbone occur in different regimes of the precession frequency of EPs. In certain ranges of the plasma rotation speed and the EPs' beta, a mode conversion can occur between the resistive wall mode and FLM.
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Affiliation(s)
- G Z Hao
- Southwestern Institute of Physics, Chengdu, China
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14
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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. PHYSICAL REVIEW LETTERS 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] [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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Berkery JW, Sabbagh SA, Betti R, Bell RE, Gerhardt SP, LeBlanc BP, Yuh H. Effect of collisionality on kinetic stability of the resistive wall mode. PHYSICAL REVIEW LETTERS 2011; 106:075004. [PMID: 21405523 DOI: 10.1103/physrevlett.106.075004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2011] [Indexed: 05/30/2023]
Abstract
The impact of collisionless, energy-independent, and energy-dependent collisionality models on the kinetic stability of the resistive wall mode is examined for high pressure plasmas in the National Spherical Torus Experiment. Future devices will have decreased collisionality, which previous stability models predict to be universally destabilizing. In contrast, in kinetic theory reduced ion-ion collisions are shown to lead to a significant stability increase when the plasma rotation frequency is in a stabilizing resonance with the ion precession drift frequency. When the plasma is in a reduced stability state with rotation in between resonances, collisionality will have little effect on stability.
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Affiliation(s)
- J W Berkery
- Department of Applied Physics and Applied Mathematics, Columbia University, New York, New York 10027, USA
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