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Long Pulse High Performance Plasma Scenario Development for the National Spherical Torus Experiment

Description: The National Spherical Torus Experiment [Ono et al., Nucl. Fusion, 44, 452 (2004)] is targeting long pulse high performance, noninductive sustained operations at low aspect ratio, and the demonstration of nonsolenoidal startup and current rampup. The modeling of these plasmas provides a framework for experimental planning and identifies the tools to access these regimes. Simulations based on neutral beam injection (NBI)-heated plasmas are made to understand the impact of various modifications a… more
Date: January 1, 2006
Creator: Kessel, C.E.; Bell, R.E.; Bell, M.G.; Gates, D.A. & Harvey, R.W.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Gyrokinetic Simulation of Global Turbulent Transport Properties in Tokamak Experiments

Description: A general geometry gyro-kinetic model for particle simulation of plasma turbulence in tokamak experiments is described. It incorporates the comprehensive influence of noncircular cross section, realistic plasma profiles, plasma rotation, neoclassical (equilibrium) electric fields, and Coulomb collisions. An interesting result of global turbulence development in a shaped tokamak plasma is presented with regard to nonlinear turbulence spreading into the linearly stable region. The mutual interact… more
Date: January 1, 2006
Creator: Wang, W. X.; Lin, Z.; Tang, W. M.; Lee, W. W.; Ethier, S.; Lewandowski, J. L. V. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Double Gap Alfvén Eigenmodes: Revisiting Eigenmodes Interaction with the Alfvén Continuum

Description: A new type of global shear Alfvén Eigenmode is found in tokamak plasmas where the mode localization is in the region intersecting the Alfvén continuum. The eigenmode is formed by the coupling of two solutions from two adjacent gaps (akin to potential wells) in the shear Alfvén continuum. For tokamak plasmas with reversed magnetic shear it is shown that the toroidiciy-induced solution tunnels through the continuum to match the ellipticity-induced Alfvén eigenmode (TAE and EAE, respectively) so t… more
Date: December 1, 2005
Creator: Gorelenkov, N. N.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Final Report for Grant No. DE-FG02-03ER54706 "Support for the 7th Workshop on The Interrelationship between Plasma Experiment in Laboratory and Space"

Description: We describe the support given to support the 7th IPELS meeting which brings together space and laboratory based physicists. The meeting was a great success with more than 80 attendees and a significant number of young scientists. The major topics of discussion were magnetic reconnection, plasma turbulence, and waves in plasmas.
Date: September 13, 2005
Creator: Kletzing, C.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Mode-conversion induced tearing effects in a plasma neutral sheet

Description: A new collisionless dissipation mechanism which can drive tearing modes in a plasma neutral sheet is described. The new mechanism relies on the presence of a background cold plasma which leads to mode conversion into a continuous spectrum of cold plasma waves.
Date: January 1, 1981
Creator: Kaw, P.K. & Sudan, R.N.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Final Report of MBX experiment

Description: The MBX experiment was built during the grant period. Details can be found in publications about MBX experiment. We created a low density plasma in a mirror configuration and rotated it at supersonic speeds in the theta direction. Under these conditions the plasma presents a high asymmetry in the current, plasma potential and consequently rotation with the voltage applied. We developed a two fluid model to describe the measurements based on a magnetofluid states ansatz. We also observed bistabl… more
Date: April 2, 2007
Creator: Bengtson, Roger D & Valanju, Prashant
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Measurements of Secondary Electron Emission Effects in the Hall Thruster Discharge

Description: The dependence of the maximum electron temperature on the discharge voltage is studied for two Hall thruster configurations, in which a collisionless plasma is bounded by channel walls made of materials with different secondary electron emission (SEE) properties. The linear growth of the temperature with the discharge voltage, observed in the channel with a low SEE yield, suggests that SEE is responsible for the electron temperature saturation in the thruster configuration with the channel wall… more
Date: December 1, 2005
Creator: Raitses, Y.; Smirnov, A.; Staack, D. & Fisch, N. J.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Final Report - Investigation of Intermittent Turbulence and Turbulent Structures in the Presence of Controlled Sheared Flows

Description: Final Report for grant DE-FG02-06ER54898. The dynamics and generation of intermittent plasma turbulent structures, widely known as "blobs" have been studied in the presence of sheared plasma flows in a controlled laboratory experiment.
Date: June 27, 2013
Creator: Gilmore, Mark A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Studies of Flows in Plasmas

Description: Note a pdf document "DOE-flow-final-report' should be attached. If it somehow is not please notify Walter Gekelman (gekelman@physics.ucla.edu) who will e mail it directly
Date: March 7, 2009
Creator: Gekelman, Walter; Morales, George & Maggs, James
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Self-organized T(sub)e Redistribution during Driven Reconnection Processes in High Temperature Plasmas

Description: Two-dimensional (2-D) images of electron temperature fluctuations with a high temporal and spatial resolution were employed to study the sawtooth oscillation in TEXTOR tokamak plasmas. The new findings are: 1) 2-D images revealed that the reconnection is localized and permitted the determination of the physical dimensions of the reconnection zone in the poloidal and toroidal planes. 2) The combination of a pressure driven mode and a kink instability leads to an "X-point" reconnection process. 3… more
Date: December 1, 2005
Creator: Park, H. K.; Mazzucato, E.; Luhmann, N. C. Jr.; Domier, C. W.; Xia, Z.; Munsat, T. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Theory and numerical simulations on collisionless drift instabilities in three dimensions

Description: Nonlinear behavior of the collisionless drift instabilities and the resultant anomalous plasma diffusion have been studied by means of computer simulations and analytic theory. The simulation model used is a full three dimensional electrostatic model in a cylindrical geometry in an external magnetic field. Full dynamics is employed for the ion motion while the guiding center approximations are used for the motion of electrons which allows us to use rather realistic plasma parameters in the simu… more
Date: November 1, 1977
Creator: Cheng, C. Z. & Okuda, H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Dust-Plasma Interactions

Description: The objective of our theoretical research under this grant over the past 3 years was to develop new understanding in a range of topics in the physics of dust-plasma interactions, with application to space and the laboratory. We conducted studies related to the physical properties of dust, waves and instabilities in both weakly coupled and strongly coupled dusty plasmas, and innovative possible applications. A major consideration in our choice of topics was to compare theory with experiments or … more
Date: January 5, 2010
Creator: Rosenberg, M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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The Absence of Plasma in"Spark Plasma Sintering"

Description: Spark plasma sintering (SPS) is a remarkable method for synthesizing and consolidating a large variety of both novel and traditional materials. The process typically uses moderate uni-axial pressures (<100 MPa) in conjunction with a pulsing on-off DC current during operation. There are a number of mechanisms proposed to account for the enhanced sintering abilities of the SPS process. Of these mechanisms, the one most commonly put forth and the one that draws the most controversy involves the… more
Date: April 10, 2008
Creator: Hulbert, Dustin M.; Anders, Andre; Dudina, Dina V.; Andersson, Joakim; Jiang, Dongtao; Unuvar, Cosan et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Modelling multi-ion plasma gun simulations of Tokamak disruptions

Description: The effect of impurity ions in plasma gun ablation tests of various targets is considered. Inclusion of reasonable amounts of impurity ({approximately}10%) is adequate to explain observed energy transmission and erosion measurements. The gun tests and the computer code calculations are relevant to the parameter range expected for major disruptions on large tokamaks.
Date: August 1, 1995
Creator: Ehst, D.A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Final technical report on studies of plasma transport

Description: This document gives an overview of the scientific results obtained under the DOE grant, and references the journal articles which give more complete descriptions of the various topics. Recently, the research has been focused on 2-dimensional vortices and turbulence: experiments using a new camera-diagnosed electron plasma apparatus have given surprising results which both clarify and challenge theories. Here, the crossfield E x B flow of the electron plasma is directly analogous to the 2-d flow… more
Date: April 1, 1997
Creator: O`Neil, T.M.; Driscoll, C.F. & Malmberg, J.H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Tapered plasma channels to phase-lock accelerating and focusing forces in laser-plasma accelerators

Description: Tapered plasma channels are considered for controlling dephasing of a beam with respect to a plasma wave driven by a weakly-relativistic, short-pulse laser. Tapering allows for enhanced energy gain in a single laser plasma accelerator stage. Expressions are derived for the taper, or longitudinal plasma density variation, required to maintain a beam at a constant phase in the longitudinal and/or transverse fields of the plasma wave. In a plasma channel, the phase velocities of the longitudinal a… more
Date: May 17, 2010
Creator: Rittershofer, W.; Schroeder, C. B.; Esarey, E.; Gruner, F. J. & Leemans, W. P.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Gyrokinetic Theory for Arbitrary Wavelength Electromagnetic Modes in Tokamaks

Description: A linear gyrokinetic system for arbitrary wavelength electromagnetic modes is developed. A wide range of modes in inhomogeneous plasmas, such as the internal kink modes, the toroidal Alfvén eigenmode (TAE) modes, and the drift modes, can be recovered from this system. The inclusion of most of the interesting physical factors into a single framework enables us to look at many familiar modes simultaneously and thus to study the modifications of and the interactions between them in a systematic wa… more
Date: October 1, 1997
Creator: Qin, H.; Rewoldt, G. & Tang, W.M.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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High beta tokamaks. [MHD equilibrium, stability, and transport calculations]

Description: MHD equilibrium, stability, and transport calculations are made to study the accessibility and behavior of ''high beta'' tokamak plasmas in the range ..beta.. approximately 5 to 15 percent. For next generation devices, beta values of at least 8 percent appear to be accessible and stable if there is a conducting surface nearby.
Date: January 1, 1978
Creator: Dory, R. A.; Berger, D. P.; Charlton, L. A.; Hogan, J. T.; Munro, J. K.; Nelson, D. B. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Experimental Investigation of Active Feedback Control of Turbulent Transport in a Magnetized Plasma

Description: A new and unique basic plasma science laboratory device - the HelCat device (HELicon-CAThode) - has been constructed and is operating at the University of New Mexico. HelCat is a 4 m long, 0.5 m diameter device, with magnetic field up to 2.2 kG, that has two independent plasmas sources - an RF helicon source, and a thermionic cathode. These two sources, which can operate independently or simultaneously, are capable of producing plasmas with a wide range of parameters and turbulence characterist… more
Date: July 7, 2013
Creator: Gilmore, Mark Allen
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Stability and magnetic tearing of finite-. beta. modified drift waves

Description: A new simplified approach to the analysis of radial eigenmodes of finite-..beta.. modified drift waves in a sheared magnetic field is described. Applying this approach to the universal drift mode, one recovers, for the lowest (n = 0) radial eigenmode, the previous result that finite-..beta.. effects are stabilizing. For the next (n = 1) radial eigenmode, however, one finds that finite-..beta.. effects further destabilize the mode. Moreover, the corresponding mode structure exhibits nonzero radi… more
Date: October 1, 1977
Creator: Chen, L.; Hsu, J.; Kaw, P. K. & Rutherford, P. H.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Unstable universal drift eigenmodes in toroidal plasmas

Description: The eigenmode equation describing ballooning collisionless drift instabilities is analyzed both analytically and numerically. A new branch of eigenmodes, which corresponds to quasi-bound states due to the finite toroidicity, is shown to be destabilized by electron Landau damping for typical Tokamak parameters. This branch cannot be understood by the strong coupling approximation. However, the slab-like (Pearlstein-Berk type) branch is found to remain stable and experience enhanced shear damping… more
Date: August 1, 1979
Creator: Cheng, C. Z. & Chen, L.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Maryland Controlled Fusion Research Program. Progress report, November 1, 1992--October 31, 1995

Description: In the past three years, members of the Maryland Plasma Theory Group have made significant contributions to the national fusion theory program, and, in many cases, these theoretical developments helped to interpret experimental results and to design new experimental programs. In this report, they summarize the technical progress in four major areas of tokamak research: (a) L/H transition and edge turbulence and transport; (b) active control of micro-turbulence and transport; (c) major disruptio… more
Date: May 1, 1995
Creator: Antonsen, T. M. Jr.; Drake, J. F.; Guzdar, P.; Hassam, A.; Liu, C. S. & Ott, E.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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