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Author : Chuang Ren
Release : 1998
Genre :
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Book Synopsis A Study of Tearing Modes Via Electron Cyclotron Emission from Tokamak Plasmas by : Chuang Ren
Download or read book A Study of Tearing Modes Via Electron Cyclotron Emission from Tokamak Plasmas written by Chuang Ren. This book was released on 1998. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Release : 1998
Genre :
Kind : eBook
Book Rating : /5 ( reviews)
Book Synopsis A Study of Tearing Modes Via Electron Cyclotron Emission from Tokamak Plasmas by :
Download or read book A Study of Tearing Modes Via Electron Cyclotron Emission from Tokamak Plasmas written by . This book was released on 1998. Available in PDF, EPUB and Kindle. Book excerpt: This thesis studies several tearing mode problems from both theoretical and experimental points of view. A major part of this thesis is to demonstrate that Electron Cyclotron Emission (ECE) is an excellent diagnostic for studying an MHD mode structure and its properties in a tokamak plasma. It is shown that an MHD mode can be detected from the electron temperature fluctuations measured by ECE. The amplitude and phase profiles of the fluctuations contain detailed information about the mode structure. The ECE fluctuation phase profile indicates the magnetic island deformation due to the combination of sheared flow and viscosity. A model is presented to relate qualitatively the observed phase gradient to the local magnetic field, flow velocity shear and viscosity in a 2D slab geometry, using an ideal Ohm's law and the plasma momentum equation including flow and viscosity. Numerical solution of the resultant Grad-Shafranov-like equation describing the deformed island shows that the experimentally observed value of the phase gradient can be obtained under realistic parameters for the shear in the flow velocity and viscosity. A new approach to the tearing mode stability boundary and saturation level is also presented.
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Release : 1994
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Book Synopsis Helical Temperature Perturbations Associated with Tearing Modes in Tokamak Plasmas by :
Download or read book Helical Temperature Perturbations Associated with Tearing Modes in Tokamak Plasmas written by . This book was released on 1994. Available in PDF, EPUB and Kindle. Book excerpt: An investigation is made into the electron temperature perturbations associated with tearing modes in tokamak plasmas, with a view to determining the mode structure using Electron Cyclotron Emission (ECE) data. It is found that there is a critical magnetic island width below which the conventional picture where the temperature is flattened inside the separatrix is invalid. This effect comes about because of the stagnation of magnetic field lines in the vicinity of the rational surface and the finite parallel thermal conductivity of the plasma. For islands whose widths lie below the critical value there is no flattening of the electron temperature inside the separatrix. Such islands have quite different ECE signatures to conventional magnetic islands. In fact the two island types could, in principle, be differentiated experimentally. It should also be possible to map out the outer ideal magnetohydrodynamical eigenfunctions using ECE data. Islands whose widths are much less than the critical value are not destabilized by the perturbed bootstrap current, unlike conventional magnetic islands. This effect is found to have a number of very interesting consequences and may, indeed, provide an explanation for some puzzling experimental results regarding error field induced magnetic reconnection. All islands whose widths are much greater than the critical width possess a boundary layer on the separatrix which enables heat to be transported from one side of the island to the other via the X-point region. The structure of this boundary layer is described in some detail. Finally, the critical island width is found to be fairly substantial in conventional tokamak plasmas, provided that the long mean free path nature of parallel heat transport and the anomalous nature of perpendicular heat transport are taken into account in the calculation.
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Release : 1997
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Book Synopsis Neoclassical Tearing Modes in Tokamak Fusion Test Reactor Experiments Part I. Measurements of Magnetic Islands and Delta Prime by :
Download or read book Neoclassical Tearing Modes in Tokamak Fusion Test Reactor Experiments Part I. Measurements of Magnetic Islands and Delta Prime written by . This book was released on 1997. Available in PDF, EPUB and Kindle. Book excerpt: Tearing type modes are observed in most high-confinement operation regimes in TFTR. Three different methods are used to measure the magnetic island widths: external magnetic coils, internal temperature fluctuation from electron cyclotron emission (ECE) diagnostic and an experiment where the plasma major radius is rapidly shifted ('Jog' experiments). A good agreement between the three methods is observed. Numerical and analytic calculations of delta prime (the tearing instability index) are compared with an experimental measurement of delta prime using the tearing mode eigenfunction mapped from the Jog data. The obtained negative delta prime indicates that the observed tearing modes cannot be explained by the classical current-gradient-driven tearing theory.
Author : Richard Fitzpatrick
Release : 2023
Genre : SCIENCE
Kind : eBook
Book Rating : 670/5 ( reviews)
Book Synopsis Tearing Mode Dynamics in Tokamak Plasmas by : Richard Fitzpatrick
Download or read book Tearing Mode Dynamics in Tokamak Plasmas written by Richard Fitzpatrick. This book was released on 2023. Available in PDF, EPUB and Kindle. Book excerpt: The development of humankind's ultimate energy source, nuclear fusion, has proceeded slowly but surely over the course of the last 60 years. This comprehensive book aims to outline a realistic, comprehensive, self-consistent, analytic theory of tearing mode dynamics in tokamak plasmas. It discusses a fluid theory of a highly magnetized plasma that treats the electrons and ions as independent fluids, and then proceeds to develop the theory of tearing modes, first approximating the geometry of a tokamak plasma as a periodic cylinder, but eventually considering the toroidal structure of real tokamak plasmas. This book also describes the stability of tearing modes, the saturation of such modes, and the evolution of their phase velocity due to interaction with other tearing modes, as well as the resistive vacuum vessel, and imperfections in the tokamak's magnetic field. This text will appeal to scientists and graduate students engaged in nuclear fusion research, and would make a useful reference for graduate plasma physics courses. Part of IOP Series in Plasma Physics.
