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Showing 1 to 20 of 31 for “"tokamak plasmas"”.
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H-Mode Transport of Tokamak Plasmas
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Rotation generation and transport in tokamak plasmas
… of bi-directional rotation on a single tokamak. These observations help to explain differences in rotation seen among the various devices running lower hybrid. The LHCD rotation reverses direction as a function of plasma current, and this occurs in a similar parameter space as the Ohmic …
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Effects of suprathermal fusion particles in tokamak plasmas
… is derived for a low-B, symmetric (non-ripple) tokamak. Velocity-space scattering is ignored. Among the important implications of this theory are: (1) the net inward drift of fusion particles during their slow-down phase, and (2) the importance of the plasma density and temperature in …
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Experimental Inference of Particle Transport in Tokamak Plasmas
The achievement of sustainable operation in tokamaks depends crucially on accurate understanding of fuel, impurity, and neutral particle dynamics. In this work, radial profiles of experimental particle transport coefficients have been inferred following laser blow-off (LBO) impurity injections into …
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Thermonuclear Driven Fast Magnetosonic Wave Heating in Tokamak Plasmas
… magnetosonic wave instability is investigated in tokamak plasmas for propagation transverse to the external magnetic field at frequencies of several times the alpha particle gyro rate: (omega)(TURNEQ)L(OMEGA)(, ) =k(,(PERP))v(,A), L(TURN)4 to 8, k(,(PARLL))<<k(,(PERP)). The 2-D differential …
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Experimental tests of parallel impurity transport theory in Tokamak plasmas
In realistic reactor scenarios, high temIperature plasmas will be composed of not only the fusion reactants and products, but also inpurities introduced purposefully or uninitentionally from plasma facing materials. In tokamaks it is often assumed, sometimes erroneously, that surfaces of constant …
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Systematic calibration of a theory-based transport model of tokamak plasmas
… of flux-surface-averaged radial transport in tokamaks has been constructed and calibrated against a well documented set of temperature and density profiles from a pre-defined set of twelve discharges from seven different tokamaks. The transport theory includes neoclassical, $\rm …
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A study on the ion temperature gradient driven turbulence in tokamak plasmas
… to confine the plasma using magnetic fields. The tokamak is the device that produces the best results concerning plasma magnetic confinement to date. One of the main tasks of fusion research is the understanding of plasma confinement. The energy confinement must be sufficiently good such that a …
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Test particle studies of acceleration and transport in solar and tokamak plasmas
… tungsten ions are also simulated) in spherical tokamak (ST) plasmas with transonic and subsonic toroidal flows. The efficacy of this approach is demonstrated by reproduscing the results of classical transport theory in the large aspect ratio limit. The equilibrium parameters used in the ST …
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Interpretable Machine Learning for Prediction and Avoidance of Disruptions in Tokamak Plasmas
Tokamak plasmas are sometimes terminated due to off-normal events called disruptions, which are characterized by successive thermal and current quench events that deplete the stored thermal and magnetic energy. In addition to the costs of disruptions due to loss of confinement and operation, their …
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Experimental study of tokamak plasmas with external rotational transform of the magnetic field
Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Physics, 1980.
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Turbulence and transport measurements in Alcator C-Mod and comparisons with Gyrokinetic simulations
Turbulence in tokamak plasmas is the primary means by which energy is transported from the core of the plasma to the edge, where it is lost, and is therefore the main limitation of tokamak plasma performance. Dilution of the main-ion species was found to have a stabilizing effect on ion gyroradius …
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Studies of electron temperature fluctuations in the core of Alcator C-Mod plasmas via correlation electron cyclotron emission
Transport in tokamak plasmas is higher than predicted by neoclassical theory; this anomalous transport is believed to be attributed to turbulent fluctuations. New Correlation Electron Cyclotron Emission (CECE) experiments on Alcator C-Mod show lower levels of electron temperature fluctuations in …
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Electron Bernstein wave current drive modeling in toroidal plasma confinement
The steady-state confinement of tokamak plasmas in a fusion reactor requires non-inductively driven toroidal currents. Radio frequency waves in the electron cyclotron (EC) range of frequencies can drive localized currents and are thus particularly attractive for control of the current profile. In …
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Mathematical and Computational Models for Transient Magnetohydrodynamic Flows of Magnetically Confined Plasmas
… modelling simulations of magnetically confined tokamak plasmas for fusion applications. Specifically, this work focuses on the solution of a nonlinear set of partial differential equations, using explicit time integration and a finite volume approach on a Cartesian grid taking advantage of …
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Rotating magnetohydrodynamic and trapped hot-ion induced internal kinks
As a new and significant contribution to the tokamak literature, the linear internal MHD kink modes in finite aspect-ratio axisymmetric toroidally rotating tokamak equilibria and their kinetic modifications owing to the presence of hot ions are computationally studied herein using a bilinear form …
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Axisymmetric equilibrium and stability analysis in Alcator C-Mod, including effects of current profile, measurement noise and power supply saturation
The vertical position of elongated tokamak plasmas is unstable on the time scale of the eddy currents in the axisymmetric conducting structures. In the absence of feedback control, the plasma would drift vertically and quench on the wall, a situation known as Vertical Displacement Event (VDE), with …
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A study of reversed shear Alfvén eigenmodes in Alcator C-Mod with phase contrast imaging
… magnetized plasma oscillation and may exist in tokamak plasmas as eigenmodes with a global structure and discrete frequencies. The inhomogeneity of the plasma profiles in conjunction with tokamak geometry tends to focus the Alfvén waves in regions of near uniformity defined by local extrema in …
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Edge transport barrier studies on the Alcator C-Mod tokamak
Edge transport barriers (ETBs) in tokamak plasmas accompany transitions from low confinement (L-mode) to high confinement (H-mode) and exhibit large density and temperature gradients in a narrow pedestal region near the last closed flux surface (LCFS). Because tokamak energy confinement depends …
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Nonlinear gyrokinetic simulations of intrinsic rotation in up-down asymmetric tokamaks
Experiments and theory show that tokamak plasmas with strong toroidal rotation and rotation shear can suppress turbulent energy transport as well as allow violation of the Troyon [beta] limit. However, using external neutral beams to inject toroidal momentum, as is done in many current experiments, …
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