Magnetized Plasma Pressure Filaments

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Magnetized Plasma Pressure Filaments

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Author : Scott Graham Karbashewski
language : en
Publisher:
Release Date : 2021

Magnetized Plasma Pressure Filaments written by Scott Graham Karbashewski and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021 with Plasma (Ionized gases) categories.

One of the prominent areas of interest in current plasma science is focused on understanding the mechanisms of heat transport beyond classical Coulomb collisions. The topic has applications in many areas of plasma physics, such as the solar corona and nuclear fusion devices. In strongly magnetized plasmas the thermal conductivity parallel to the magnetic field is numerically quite large and orders of magnitude larger than the transverse conductivity; thus, the effective study of heat transport in these conditions requires a large system that is much longer along the magnetic axis than across. In this thesis, results are presented from basic heat transport experiments using magnetized plasma pressure filaments. The experiments are performed in the Large Plasma Device (LAPD) at the Basic Plasma Science Facility (BaPSF) at the University of California, Los Angeles (UCLA). A cerium hexaboride crystal cathode injects low-energy electrons along a magnetic field into the centre of a preexisting, cold, quiescent plasma forming a hot electron filament embedded in a colder plasma. Previous experiments observed gradient-driven drift-Alfvén waves that lead to enhanced cross-field transport; and a spontaneous thermal diffusion wave that was speculated to meet a quarter-wave resonance of the filament length. In the first set of experiments, a low amplitude sinusoidal perturbation is added to the cathode discharge bias that creates an oscillating heat source capable of driving large amplitude electron temperature oscillations. Langmuir probes are used to measure the amplitude and phase of the thermal wave field over a wide range of driver frequencies. The results are used to verify the excitation of thermal waves in magnetized plasma and confirm the presence of thermal resonances of the filament. The diagnostic potential of thermal waves is demonstrated through measurement of the parallel thermal diffusivity and distinguishing between classical transport, drift-Alfvén growth, and turbulent transport regimes using the cross-field structure. Two models for the thermal wave field are investigated and used to describe the experiment results; a two-dimensional homogeneous model based on a Green function approach and a one-dimensional inhomogeneous model based on a classical mechanics approach using the Hamilton-Jacobi equation. The second set of experiments have used three crystal cathodes in a triangular configuration to investigate the interactions between multiple pressure filaments with varying separation distances. The results are used to establish the scale length of interaction between the filaments. Within an electron skin depth, enhanced cross-field transport from chaotic E × B mixing rapidly relaxes the gradients in the inner triangular region of the filaments and leads to the growth of global nonlinear drift-Alfvén modes that are driven by the thermal gradient in the outer region of the filament bundle. Linear stability analysis of the temperature, density, and transverse flow profiles is used to accurately predict the observed wave modes. Coupling between the global modes leads to large intermittent transport events that are characterized by exponential frequency spectra and Lorentzian-shaped pulses that are signatures of chaotic dynamics. Mode decomposition and conditional averaging are used to reconstruct the pulse events and demonstrate that they are driven by nonlinear interactions between drift-Alfvén wave modes. The time series analysis tools of the complexity-entropy plane and Hurst exponent are used to investigate the chaotic nature and memory of the intermittent fluctuations. Last, the addition of a sinusoidal driver to one of the filaments in the configuration facilitates driving of the drift-Alfvén modes. The driver is shown to synchronize with several eigenmodes at once due to the asymmetric perturbation.

Electromagnetic And Kinetic Effects On Blob Filamentary Plasma Structures In Magnetic Confinement Devices

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Author : Wonjae Lee
language : en
Publisher:
Release Date : 2017

Electromagnetic And Kinetic Effects On Blob Filamentary Plasma Structures In Magnetic Confinement Devices written by Wonjae Lee and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017 with categories.

Plasma blobs (filamentary structures extended along the magnetic field lines) are mesoscale turbulent structures that are usually observed in the scrape-off layer (SOL) of magnetic confinement devices. Electromagnetic fluid simulations for seeded high-beta blobs demonstrate that inhomogeneity of magnetic curvature or plasma pressure along the filament leads to bending of the filaments and magnetic field lines due to increased Alfven time. Moreover, the drift wave instabilities inside the filaments are modified by electromagnetic effects. A local linear analysis on an electromagnetic drift-kinetic equation with BGK-like collision operator proves to be valid for describing the linear growth rate of drift wave instabilities in a wide range of plasma parameters showing convergence to reference models for limiting cases. Finally, the development of the 5D version of the full-f gyrokinetic code COGENT and its application to the collisionless drift wave simulation are presented with discussion of the disturbance of the distribution function from the collisionless drift wave instability and the formation of a helical mode structure within the plasma filament.

Heat Transport Of A Temperature Filament In A Magnetized Plasma

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Author : Meixuan Shi
language : en
Publisher:
Release Date : 2009

Heat Transport Of A Temperature Filament In A Magnetized Plasma written by Meixuan Shi and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2009 with categories.

Electromagnetic Effects On Dynamics Of High Beta Filamentary Structures

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Author :
language : en
Publisher:
Release Date : 2015

Electromagnetic Effects On Dynamics Of High Beta Filamentary Structures written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2015 with categories.

The impacts of the electromagnetic effects on blob dynamics are considered. Electromagnetic BOUT++ simulations on seeded high-beta blobs demonstrate that inhomogeneity of magnetic curvature or plasma pressure along the filament leads to bending of the blob filaments and the magnetic field lines due to increased propagation time of plasma current (Alfvén time). The bending motion can enhance heat exchange between the plasma facing materials and the inner SOL region. The effects of sheath boundary conditions on the part of the blob away from the boundary are also diminished by the increased Alfvén time. Using linear analysis and the BOUT++ simulation, it is found that electromagnetic effects in high temperature and high density plasmas reduce the growth rate of resistive drift wave turbulence when resistivity drops below some certain value. Lastly, in the course of blobs motion in the SOL its temperature is reduced, which leads to enhancement of resistive effects, so the blob can switch from electromagnetic to electrostatic regime, where resistive drift wave turbulence become important.

Turbulent Transport In Magnetized Plasmas Second Edition

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Author : Horton, Jr C Wendell
language : en
Publisher: #N/A
Release Date : 2017-07-21

Turbulent Transport In Magnetized Plasmas Second Edition written by Horton, Jr C Wendell and has been published by #N/A this book supported file pdf, txt, epub, kindle and other format this book has been release on 2017-07-21 with Science categories.

For a few seconds with large machines, scientists and engineers have now created the fusion power of the stars in the laboratory and at the same time find the rich range of complex turbulent electromagnetic waves that transport the plasma confinement systems. The turbulent transport mechanisms created in the laboratory are explained in detail in the second edition of "Turbulent Transport in Magnetized Plasmas" by Professor Horton. The principles and properties of the major plasma confinement machines are explored with basic physics to the extent currently understood. For the observational laws that are not understood — the empirical confinement laws — offering challenges to the next generation of plasma students and researchers — are explained in detail. An example, is the confinement regime — called the "I–mode" — currently a hot topic — is explored. Numerous important problems and puzzles for the next generation of plasma scientists are explained. There is growing demand for new simulation codes utilizing the massively parallel computers with MPI and GPU methods. When the 20 billion dollar ITER machine is tested in the 2020ies, new theories and faster/smarter computer simulations running in near real-time control systems will be used to control the burning hydrogen plasmas.

Pressure Distribution And Stability Of A Magnetized Plasma With Neutral Gas Blanket

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Author : B. Lehnert
language : en
Publisher:
Release Date : 1973

Pressure Distribution And Stability Of A Magnetized Plasma With Neutral Gas Blanket written by B. Lehnert and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1973 with categories.

Momentum Balance For Current Filaments In Magnetic Fields

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Author : Herbert O. Schrade
language : en
Publisher:
Release Date : 1968

Momentum Balance For Current Filaments In Magnetic Fields written by Herbert O. Schrade and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1968 with Electric arc categories.

Based on the momentum equation, the impulse transport from a current-carrying plasma filament to the surrounding nonconductive gas is found to be a function of the current, the magnetic field, the filament radius and the radius of curvature of the current streamer. This impulse transport normal to the discharge axis per unit time and length arises from convective and/or diffusive interactions between the filament and its nonconductive environment. The momentum exchange per unit filament represents a transverse force varying between zero and IBo. It may become zero if the Lorentz force is balanced by the inertia of the current-carrying particles within the filament; conversely, it reaches a maximum when the Lorentz force is opposed by gas dynamic reaction forces between the filament and the surrounding plasma. This latter case usually occurs when the motion of electrons and ions within the filament is collision-dominated and no net axial plasma flow is present. Since the transverse exchange mode constitutes a known balance of forces, one is able to determine the curvature behavior and the shape of a filament in a given magnetic field configuration. Characteristic stable filament structures are presented. (Author).

Issues In Nuclear High Energy Plasma Particle And Condensed Matter Physics 2011 Edition

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Author :
language : en
Publisher: ScholarlyEditions
Release Date : 2012-01-09

Issues In Nuclear High Energy Plasma Particle And Condensed Matter Physics 2011 Edition written by and has been published by ScholarlyEditions this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-01-09 with Science categories.

Issues in Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics: 2011 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics. The editors have built Issues in Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics: 2011 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Momentum Balance For Current Filaments In Magnetic Fields

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Author : Herbert O. Schrade
language : en
Publisher:
Release Date : 1968

Momentum Balance For Current Filaments In Magnetic Fields written by Herbert O. Schrade and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1968 with Electric arc categories.

Based on the momentum equation, the impulse transport from a current-carrying plasma filament to the surrounding nonconductive gas is found to be a function of the current, the magnetic field, the filament radius and the radius of curvature of the current streamer. This impulse transport normal to the discharge axis per unit time and length arises from convective and/or diffusive interactions between the filament and its nonconductive environment. The momentum exchange per unit filament represents a transverse force varying between zero and IBo. It may become zero if the Lorentz force is balanced by the inertia of the current-carrying particles within the filament; conversely, it reaches a maximum when the Lorentz force is opposed by gas dynamic reaction forces between the filament and the surrounding plasma. This latter case usually occurs when the motion of electrons and ions within the filament is collision-dominated and no net axial plasma flow is present. Since the transverse exchange mode constitutes a known balance of forces, one is able to determine the curvature behavior and the shape of a filament in a given magnetic field configuration. Characteristic stable filament structures are presented. (Author).

Tokamak Plasma

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Author : B. B. Kadomtsev
language : en
Publisher: CRC Press
Release Date : 1992

Tokamak Plasma written by B. B. Kadomtsev and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 1992 with Art categories.

The importance of tokamaks and their role in fusion reactors has been known for some time, but it is only now that plasma physicists have reached a clear understanding of the major principles governing the behaviour of confined high-temperature plasma. This book gives a timely and comprehensive survey of these concepts as well as a simple presentation of the basic physics involved. The topics discussed include: the theory of plasma equilibrium and its main instabilities, semi-empirical approaches for investigating heat transport, major plasma instabilities restricting the region of a tokamak's operating modes, a variety of plasma confinement regimes and other phenomena such as MARFE, magnetic bubbles and fishbones. The author proposes a new mechanism for anomalous heat transport connected with the idea of microscale 'island' structure. The information is presented in a clear and systematic way which will make this book interesting and useful to a broad spectrum of scientists and engineers involved in fusion reactor research. '...an excellent book - authoritative, broad and bristling with insight' Professor R D Hazeltine, The University of Texas at Austin.