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in subjects: "Alfven Waves"  
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Continuum damping of low-n toroidicity-induced shear Alfven eigenmodes

Description: The effect of resonant continuum damping is investigated for the low-mode-number, toroidicity-induced, global shear Alfven eigenmodes, which can be self-excited by energetic circulating alpha particles in an ignited tokamak plasma. Resonant interaction with the shear Alfven continuum is possible for these eigenmodes, especially near the plasma periphery, leading to significant dissipation, which is typically larger than direct bulk plasma dissipation rates. Two perturbation methods are develope… more
Date: September 1, 1991
Creator: Berk, H.L.; Van Dam, J.W.; Guo, Z. & Lindberg, D.M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Methods of driving current by heating a toroidal plasma

Description: In addition to the usual mechanism which utilizes the Ohmic transformer current, which is necessarily pulsed, there exist several steady-state mechanisms. Heating mechanisms which can lend themselves efficiently to continuous current generation include neutral beams, Alfven waves, ion-cyclotron waves, lower-hybrid waves and electron-cyclotron waves.
Date: August 1, 1980
Creator: Fisch, N. J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Shear alfven resonances in Tokapole II

Description: It has been suggested that efficient heating can occur by coupling energy through the shear Alfven resonance that is predicted to occur at particular locations within inhomogeneous plasmas. This heating mechanism should be applicable to tokamaks; however, the existence of the resonances in tokamaks has not yet been established experimentally. We present here direct observations of localized enhancement in the driven wave magnetic field which are compatible with theoretical predictions for the s… more
Date: March 1, 1982
Creator: Witherspoon, F.D.; Prager, S.C. & Sprott, J.C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Excitation of high-n toroidicity-induced shear Alfven eigenmodes by energetic particles and fusion alpha particles in tokamaks

Description: The stability of high-n toroidicity-induced shear Alfven eigenmodes (TAE) in the presence of fusion alpha particles or energetic ions in tokamaks is investigated. The TAE modes are discrete in nature and thus can easily tap the free energy associated with energetic particle pressure gradient through wave particle resonant interaction. A quadratic form is derived for the high-n TAE modes using gyro-kinetic equation. The kinetic effects of energetic particles are calculated perturbatively using t… more
Date: July 1, 1992
Creator: Fu, G. Y. & Cheng, C. Z.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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A formula for efficiency of fast wave current drive in fusion devices

Description: Fast wave current drive (FWCD) is a principal candidate for non- inductive current drive schemes in reactors. Major experiments are in progress or planned on DIII-D, JET, and Tore-Supra. A theory for FWCD was presented by two of the authors and collaborators. To minimize computations required in transport simulations, and for analytical understanding, it is very useful to have a concise analytical efficiency formula. Fisch and Karney, and Ehst and Karney have obtained empirical formulae that fi… more
Date: June 1, 1992
Creator: Chiu, S. C.; Harvey, R. W. (General Atomics, San Diego, CA (United States)); Karney, C. F. F. (Princeton Univ., NJ (United States). Plasma Physics Lab.) & Mau, T. K. (California Univ., Los Angeles, CA (United States). School of Engineering and Applied Science)
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Partner: UNT Libraries Government Documents Department
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Very high Mach number shocks: theory

Description: The theory and simulation of collisionless perpendicular supercritical shock structure is reviewed, with major emphasis on recent research results. The primary tool of investigation is the hybrid simulation method, in which the Newtonian orbits of a large number of ion macroparticles are followed numerically, and in which the electrons are treated as a charge neutralizing fluid. The principal results to be presented are (1) electron resistivity is not required to explain the observed quasi-stat… more
Date: January 1, 1986
Creator: Quest, K. B.
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Partner: UNT Libraries Government Documents Department
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Axisymmetric instability in a noncircular tokamak

Description: The stability of dee, inverse-dee and square cross section plasmas to axisymmetric modes has been investigated experimentally in Tokapole II, a tokamak with a four-null poloidal divertor. Experimental results are closely compared with predictions of two numerical stability codes - the PEST code (ideal MHD, linear stability) adapted to tokapole geometry and a code which follows the nonlinear evolution of shapes similar to tokapole equilibria.
Date: October 1, 1979
Creator: Lipschultz, B.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Flow shear suppression of turbulence using externally driven ion Bernstein and Alfven waves

Description: The utilization of externally-launched radio-frequency waves as a means of active confinement control through the generation of sheared poloidal flows is explored. For low-frequency waves, kinetic Alfven waves are proposed, and are shown to drive sheared E {times} B flows as a result of the radial variation in the electromagnetic Reynolds stress. In the high frequency regime, ion Bernstein waves are considered, and shown to generate sheared poloidal rotation through the ponderomotive force. In … more
Date: January 1, 1991
Creator: Biglari, H.; Ono, M. (Princeton Univ., NJ (United States). Plasma Physics Lab.); Diamond, P.H. (California Univ., San Diego, La Jolla, CA (United States). Dept. of Physics) & Craddock, G.G. (Science Applications International Corp., San Diego, CA (United States))
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Alfven wave stability in D-III-D

Description: Within the framework of the global Alfven eigenmode theory in a cylindrical background plasma, I examine the excitation of global Alfven eigenmodes by intense neutral beam injection in the D III-D tokamak operating at General Atomics. I have considered two separate sets of experimental conditions, a low power'' set of cases using 10MW of hydrogen beams, and a high power'' shot of 20MW of deuterium beams. My results are particularly sensitive to the background density profile. For parabolic back… more
Date: September 1, 1989
Creator: Campbell, R.B. (Lawrence Livermore National Lab., CA (USA)) & Samec, T.K. (TRW, Inc., Redondo Beach, CA (USA))
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Computer simulations of anomalous transport

Description: Numerical plasma simulations have been carried out to study: (1) the turbulent spectrum and anomalous plasma transport associated with a steady state electrostatic drift turbulence; and (2) the anomalous energy transport of electrons due to shear-Alfven waves in a finite-..beta.. plasma. For the simulation of the steady state drift turbulence, it is observed that, in the absence of magnetic shear, the turbulence is quenched to a low level when the rotational transform is a rational number, whil… more
Date: July 1, 1980
Creator: Lee, W. W. & Okuda, H.
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Partner: UNT Libraries Government Documents Department
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Alfven wave. DOE Critical Review Series

Description: This monograph deals with the properties of Alfven waves and with their application to fusion. The book is divided into 7 chapters dealing with linear properties in homogeneous and inhomogeneous plasmas. Absorption is treated by means of kinetic theory. Instabilities and nonlinear processes are treated in Chapters 1 to 6, and the closing chapter is devoted to theory and experiments in plasma heating by Alfven waves. (MOW)
Date: January 1, 1982
Creator: Hasegawa, A. & Uberoi, C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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On resonant destabilization of toroidal Alfven eigenmodes by circulating and trapped energetic ions/alpha particles in tokamaks

Description: Toroidal Alfven eigenmodes are shown to be resonantly destabilized by both circulating and trapped energetic ions/alpha particles. In particular, the energetic circulating ions are shown to resonate with the mode not only at the Alfven speed ({upsilon}{sub A}), but also one-third of this speed, while resonances exist between trapped energetic ions and the wave when {upsilon} = {upsilon}{sub A}/21{epsilon}{sup {1/2}} (l=integer, {epsilon}=r/R is the local inverse aspect ratio), although the inst… more
Date: October 1, 1991
Creator: Biglari, H.; Zonca, F. & Chen, L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Review of plasma heating by waves in the ion-cyclotron range of frequencies

Description: Three aspects of wave heating in the Ion-Cyclotron Range of Frequencies are reviewed. First, the many interesting physics phenomena are outlined which occur in this frequency regime and how they can be profitably utilized in tokamak and other heating experiments is indicated. Second, the key current theoretical problems are enumerated. Thirdly, how the ICRF program for the PLT tokamak can address most of the physics questions is shown.
Date: January 1, 1978
Creator: Perkins, F.W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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DOE planning workshop on rf theory and computations

Description: The purpose of the two-day workshop-meeting was to review the status of rf heating in magnetic fusion plasmas and to determine the outstanding problems in this area. The term rf heating was understood to encompass not only bulk plasma heating by externally applied electromagnetic power but also current generation in toroidal plasmas and generation of thermal barriers in tandem mirror plasmas.
Date: January 1, 1984
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Nonlinear excitation of magnetostatic fluctuations by kinetic drift-Alfven waves

Description: It is shown that, for typical tokamak parameters, superthermal magnetostatic convective-cell fluctuations can be nonlinearly excited by a moderate level of kinetic drift-Alfven turbulence (e.g., delta n/n/sub 0/ approx. 1 %). Effects on the plasma cross-field transport and the nonlinear evolution of drift-Alfven turbulence are also briefly discussed.
Date: May 1, 1982
Creator: Kaw, P.K. & Chen, L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Destabilization of tokamak pressure-gradient driven instabilities by energetic alpha populations

Description: Alpha particle populations can significantly alter existing MHD in stabilities in tokamaks through kinetic effects and coupling to otherwise stable shear Alfven waves. Here we consider resonances of the trapped alpha precessional drift with both the usual ballooning mode diamagnetic frequency ({omega}{sub *i}/2) and the toroidicity induced Alfven eigenmode (TAE). This is examined for noncircular tokamaks in the high-n ballooning limit using an isotropic alpha slowing down distribution and retai… more
Date: January 1, 1989
Creator: Spong, D. A.; Holmes, J. A.; Leboeuf, J. N.; Christenson, P. J. & Michigan Univ., Ann Arbor, MI (USA). Dept. of Nuclear Engineering)
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Partner: UNT Libraries Government Documents Department
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Fusion programs in applied plasma physics

Description: The objectives of the theoretical science program are: To support the interpretation of present experiments and predict the outcome of future planned experiments; to improve on existing models and codes and validate against experimental results; and to conduct theoretical physics development of advanced concepts with applications for DIII-D and future devices. Major accomplishments in FY91 include the corroboration between theory and experiment on MHD behavior in the second stable regime of ope… more
Date: February 1, 1992
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Alpha modification of Tokamak ballooning instabilities

Description: This paper will discuss the high-n ballooning limit (drift resonant effects included in noncircular tokamak geometry) and the hybrid fluid-particle code (inhomogeneous, sheared slab geometry, full FLR alphas, linear and nonlinear).
Date: January 1, 1989
Creator: Spong, D. A.; Leboeuf, J. N.; Holmes, J. A. & Christenson, P. J.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Alfven wave. [Book on linear and nonlinear properties for fusion applications]

Description: Seven chapters are included. Chapters 1 and 2 introduce the Alfven wave and describe its linear properties in a homogeneous medium. Chapters 3 and 4 cover the effects of inhomogeneities on these linear properties. Particular emphasis is placed on the appearance of a continuum spectrum and the associated absorption of the Alfven wave which arise due to the inhomogeneity. The explanation of the physical origin of absorption is given using kinetic theory. Chapter 5 is devoted to the associated pla… more
Date: November 1, 1978
Creator: Hasegawa, A. & Uberoi, C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Propagation and Mode Conversion for Waves in Nonuniform Plasmas

Description: The following topics are described: (1) the hybrid resonance, (2) Alfven resonance, (3) the intermediate-frequency electromagnetic wave equation, (4) the standard equation, (5) the tunneling equation, (6) asymptotic solutions of the tunneling equation, (7) localized absorption, and (8) matched asymptotic expansions; the low-frequency Alfven resonance. (MOW)
Date: June 1, 1982
Creator: Stix, T. H. & Swanson, D. G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Anomalous alpha particle transport in thermonuclear tokamak plasma

Description: Due to the strong localization of the fusion born ..cap alpha..-particles in velocity and configuration space and their coupling to Alfven waves in the background plasma the relaxation of ..cap alpha..-s is anomalous. In a finite system, the enhanced electromagnetic fluctuations can produce rapid spatial losses of ..cap alpha..-population and energy. These losses prevent the ..cap alpha..-velocity distribution from attaining a stable collisional equilibrium, thus maintaining a steady state turb… more
Date: August 1, 1977
Creator: Sigmar, D. J. & Chan, M. C.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Comparison of high-n instabilities including alpha-particle effects in BPX and TFTR

Description: Three distinct types of high toroidal mode number instabilities are obtained from a comprehensive kinetic calculation, using as input transport code results from the analysis of a recent design for the Burning Plasma Experiment (BPX). These instabilities are: the collisionless trapped-electron ion-temperature-gradient mode, the magnetohydrodynamic ballooning mode, and a high toroidal mode number version of the toroidicity-induced Alfven eigenmode or gap'' mode. The dependence of the instability… more
Date: July 1, 1991
Creator: Rewoldt, G.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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