Download or read book Microtearing Instabilities and Electron Transport in the NSTX Spherical Tokamak written by and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We report a successful quantitative account of the experimentally determined electron thermal conductivity [chi]e in a beam-heated H mode plasma by the magnetic fluctuations from microtearing instabilities. The calculated [chi]e based on existing nonlinear theory agrees with the result from transport analysis of the experimental data. Without using any adjustable parameter, the good agreement spans the entire region where there is a steep electron temperature gradient to drive the instability.
Download or read book Gyrokinetic Stability Studies of the Microtearing Mode in the National Spherical Torus Experiment H mode written by Redi M. H. Baumgaertel J. A. (Budny R. V.) and published by . This book was released on 2005 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Insight into plasma microturbulence and transport is being sought using linear simulations of drift waves on the National Spherical Torus Experiment (NSTX), following a study of drift wave modes on the Alcator C-Mod Tokamak. Microturbulence is likely generated by instabilities of drift waves, which cause transport of heat and particles. Understanding this transport is important because the containment of heat and particles is required for the achievement of practical nuclear fusion. Microtearing modes may cause high heat transport through high electron thermal conductivity. It is hoped that microtearing will be stable along with good electron transport in the proposed low collisionality International Thermonuclear Experimental Reactor (ITER). Stability of the microtearing mode is investigated for conditions at mid-radius in a high density NSTX high performance (H-mode) plasma, which is compared to the proposed ITER plasmas. The microtearing mode is driven by the electron temperature gradient, and believed to be mediated by ion collisions and magnetic shear. Calculations are based on input files produced by TRXPL following TRANSP (a time-dependent transport analysis code) analysis. The variability of unstable mode growth rates is examined as a function of ion and electron collisionalities using the parallel gyrokinetic computational code GS2. Results show the microtearing mode stability dependence for a range of plasma collisionalities. Computation verifies analytic predictions that higher collisionalities than in the NSTX experiment increase microtearing instability growth rates, but that the modes are stabilized at the highest values. There is a transition of the dominant mode in the collisionality scan to ion temperature gradient character at both high and low collisionalities. The calculations suggest that plasma electron thermal confinement may be greatly improved in the low-collisionality ITER.
Download or read book Experimental Study of Parametric Dependence of Electron scale Turbulence in a Spherical Tokamak written by and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Startup and Stability of a Small Spherical Tokamak written by Gregory Douglas Garstka and published by . This book was released on 1997 with total page 420 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Electron Heat Transport in Tokamak H mode Pedestals written by Myriam Hamed and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In H-mode plasmas, the modeling of the pedestal dynamics is an important issue to predict temperature and density profiles in the tokamak edge and therefore in the core. The EPED model, based on the stability of large scales MagnetoHydroDynamic (MHD) modes, is most commonly used to characterize the pedestal region. The EPED model has been successful until now. However, EPED model does not take into account small scales instabilities linked the the sharp pressure gradient and the pedestal characteristics prediction in terms of width and height is still open. Moreover, some recent analysis of JET plasmas suggest that another class of instabilities, called microtearing modes, may be responsible for electron heat transport in the pedestal, and thereby play some role in determining the pedestal characteristics. Microtearing modes belong to a class of instabilities where a modification of the magnetic field line topology is induced at the ion Larmor radius scale. This leads to the formation of magnetic islands, which can enhance the electron heat transport. The stability of MTMs has been theoretically studied in the past showing that a slab current sheet is stable in the absence of collisions. In contrast, recent gyrokinetic simulations in toroidal geometry found unstable MTMs, even at low collisionality. The purpose of our work is to improve the MTM stability understanding by comparing new analytical theory to linear gyrokinetic simulations. More precisely, physical mechanisms (magnetic drift, electric potential) are progressively included in the analytical description to recover the numerical simulations results and to "reconcile" numerical MTM investigations with theory.
Download or read book Turbulent Electron Thermal Transport in Fusion Plasmas written by Juhyung Kim and published by . This book was released on 2008 with total page 354 pages. Available in PDF, EPUB and Kindle. Book excerpt: Electron heat transport at the scale of electron gyroradius are investigated via numerical simulation of a fluid model and a role of E x B shear flow with intermediate E x B shearing rate is explored in Euler's equation. The anomalous transport, enhanced transport due to turbulent electro-magnetic fields caused by plasma instabilities, has been a focus of the inter-national fusion research communities. Among the instabilities, the drift-type instabilities from the pressure-gradient universal in magnetic fusion devicesare considered responsible for the anomalous transport. In the current status of wide use of wave heating on electrons and subsequent high core electron temperature, the turbulent heat loss through electrons has one of the most important science element in preventing the large fusion tokamaks from reaching breakeven in the past decade. The Electron Temperature Gradient fluid model consists of electrostatic potential, toroidal magnetic flux function and electron temperature (or pressure) describing electron drift waves. The fluid model proves to be highly useful to electron heat flux analysis in fusion machines. We analyze the discharges in National Spherical Tokamak eXperiment(NSTX) and Tokamak Configuration Variable (TCV) and found that the electron thermal diffusivities can be explained in terms of the mixing length argument based on electron gyroradius, linear theory and our nonlinear fluid simulation. The nonlinear fluid model predicts reasonable heat flux observed in the experiments. Based on the analysis, we investigate the dependences of the dynamics on the ratio of electron and ion temperature T[subscript e]/T[subscript i] and plasma beta [beta subscript e-]. The nonlinear dynamics such as saturation mechanism of the ETG turbulence and the electromagnetic dynamics in terms of micro-tearing at the scale of electron gyroradius are discussed briegly. In most of plasma confinement devices, the equilibrium radial electric field exists and the turbulence-generated electric field is observed. The coherent structure, called as zonal flow, has been know to be effective to suppress the micro-turbulence. But at intermediate E x B shear, where the vortex eddy turn-over time is comparable to E x B shearing rate, the suppression is weak and the flow shear can leads to vortex amplification through interaction of nonlinear dynamics and shear flow.
Download or read book Engineering Overview of the National Spherical Torus Experiment NSTX written by and published by . This book was released on 1997 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The National Spherical Torus Experiment (NSTX) Project will provide a national facility for the study of plasma confinement, heating, and current drive in a low-aspect-ratio, spherical torus (ST) configuration. The ST configuration is an alternate confinement concept which is characterized by high beta, high elongation, high bootstrap fraction, and low toroidal magnetic field compared to conventional tokamaks. The NSTX is the next-step ST experiment following smaller experiments such as the Princeton Plasma Physics Laboratory CDX-U (Current Drive Experiment-Upgrade), the START (Small Tight Aspect Ratio Tokamak) at Culham Laboratory, UK, and the HIT (Helicity Injected Tokamak) at the University of Washington, and it is smaller in scale to the MAST (Meg-Amp Spherical Tokamak) machine now under construction at Culham. This paper provides a description of the NSTX mission and gives an overview of the main engineering features of the design of the machine and facility and discusses some of the key design solutions.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2009 with total page 840 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Fairy Tale of Nuclear Fusion written by L. J. Reinders and published by Springer Nature. This book was released on 2021-05-20 with total page 628 pages. Available in PDF, EPUB and Kindle. Book excerpt: This carefully researched book presents facts and arguments showing, beyond a doubt, that nuclear fusion power will not be technically feasible in time to satisfy the world's urgent need for climate-neutral energy. The author describes the 70-year history of nuclear fusion; the vain attempts to construct an energy-generating nuclear fusion power reactor, and shows that even in the most optimistic scenario nuclear fusion, in spite of the claims of its proponents, will not be able to make a sizable contribution to the energy mix in this century, whatever the outcome of ITER. This implies that fusion power will not be a factor in combating climate change, and that the race to save the climate with carbon-free energy will have been won or lost long before the first nuclear fusion power station comes on line. Aimed at the general public as well as those whose decisions directly affect energy policy, this book will be a valuable resource for informing future debates.
Download or read book Tokamak Start Up Problems and Scenarios Related to the Transient Phases of a Thermonuclear Fusion Reactor Ettor Majorana International Science Series written by Heinz Knoepfel and published by Springer. This book was released on 2013-12-19 with total page 425 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book contains the papers presented at the Course on "Tokamak Startup - Problems and Scenarios Related to the Transient Phases of a Thermonuclear Fusion Reactor" which was held in Erice, July 14-20, 1985. The fact that the critical startup and transient phases of a tokamak reactor are now the specific subject of a comprehensive international gathering of fusion specialists seems indicative of the substantial pro gress made in recent years towards attaining controlled ignition of a nuclear fusion fuel, i.e. towards demonstrating the scientific feasibili ty of controlled thermonuclear fusion. In fact, the steady-state burning phase has attracted so far most of the attention of fusion physicists and engineers, as it is conceptually more rewarding, and theoretically easier to handle. However, as for many large engineering systems, - nuclear fis- ... ':1' " . 10 ' ... Entrance to San Rocco's lecturing hall v sion power plants, or aerospace crafts, for example - the major issues of design and operation lie often in the startup, shutdown and power tran sieQt phases, rather than at the full load, or at cruising regimes. In ehoosing the contributions to this 7th Course of Prof. B.
Download or read book Plasma Physics and Fusion Energy written by Jeffrey P. Freidberg and published by Cambridge University Press. This book was released on 2008-07-10 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: There has been an increase in interest worldwide in fusion research over the last decade and a half due to the recognition that a large number of new, environmentally attractive, sustainable energy sources will be needed to meet ever increasing demand for electrical energy. Based on a series of course notes from graduate courses in plasma physics and fusion energy at MIT, the text begins with an overview of world energy needs, current methods of energy generation, and the potential role that fusion may play in the future. It covers energy issues such as the production of fusion power, power balance, the design of a simple fusion reactor and the basic plasma physics issues faced by the developers of fusion power. This book is suitable for graduate students and researchers working in applied physics and nuclear engineering. A large number of problems accumulated over two decades of teaching are included to aid understanding.
Download or read book Iter Physics written by C Wendell Horton, Jr and published by World Scientific. This book was released on 2015-06-25 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: The promise of a vast and clean source of thermal power drove physics research for over fifty years and has finally come to collimation with the international consortium led by the European Union and Japan, with an agreement from seven countries to build a definitive test of fusion power in ITER. It happened because scientists since the Manhattan project have envisioned controlled nuclear fusion in obtaining energy with no carbon dioxide emissions and no toxic nuclear waste products.This large toroidal magnetic confinement ITER machine is described from confinement process to advanced physics of plasma-wall interactions, where pulses erupt from core plasma blistering the machine walls. Emissions from the walls reduce the core temperature which must remain ten times hotter than the 15 million degree core solar temperature to maintain ITER fusion power. The huge temperature gradient from core to wall that drives intense plasma turbulence is described in detail.Also explained are the methods designed to limit the growth of small magnetic islands, the growth of edge localized plasma plumes and the solid state physics limits of the stainless steel walls of the confinement vessel from the burning plasma. Designs of the wall coatings and the special 'exhaust pipe' for spent hot plasma are provided in two chapters. And the issues associated with high-energy neutrons — about 10 times higher than in fission reactions — and how they are managed in ITER, are detailed.
Download or read book The British Chess Magazine Volume 16 written by Anonymous and published by Legare Street Press. This book was released on 2022-10-27 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work has been selected by scholars as being culturally important, and is part of the knowledge base of civilization as we know it. This work is in the "public domain in the United States of America, and possibly other nations. Within the United States, you may freely copy and distribute this work, as no entity (individual or corporate) has a copyright on the body of the work. Scholars believe, and we concur, that this work is important enough to be preserved, reproduced, and made generally available to the public. We appreciate your support of the preservation process, and thank you for being an important part of keeping this knowledge alive and relevant.
Download or read book Fusion Physics written by Mitsuru Kikuchi and published by . This book was released on 2012 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides an introduction to nuclear fusion and its status and prospects, and features specialized chapters written by leaders in the field, presenting the main research and development concepts in fusion physics. At over 1100 pages, this publication provides an unparalleled resource for fusion physicists and engineers.
Download or read book Plasma Scattering of Electromagnetic Radiation written by John Sheffield and published by Academic Press. This book was released on 2010-11-25 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work presents one of the most powerful methods of plasma diagnosis in exquisite detail, to guide researchers in the theory and measurement techniques of light scattering in plasmas. Light scattering in plasmas is essential in the research and development of fusion energy, environmental solutions, and electronics. Referred to as the "Bible" by researchers, the work encompasses fusion and industrial applications essential in plasma research. It is the only comprehensive resource specific to the plasma scattering technique. It provides a wide-range of experimental examples and discussion of their principles with worked examples to assist researchers in applying the theory. Computing techniques for solving basic equations helps researchers compare data to the actual experiment New material on advances on the experimental side, such as the application of high density plasmas of inertial fusion Worked out examples of the scattering technique for easier comprehension of theory
Download or read book Complex Plasmas written by Michael Bonitz and published by Springer Science & Business Media. This book was released on 2014-04-09 with total page 495 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides the reader with an introduction to the physics of complex plasmas, a discussion of the specific scientific and technical challenges they present and an overview of their potential technological applications. Complex plasmas differ from conventional high-temperature plasmas in several ways: they may contain additional species, including nano meter- to micrometer-sized particles, negative ions, molecules and radicals and they may exhibit strong correlations or quantum effects. This book introduces the classical and quantum mechanical approaches used to describe and simulate complex plasmas. It also covers some key experimental techniques used in the analysis of these plasmas, including calorimetric probe methods, IR absorption techniques and X-ray absorption spectroscopy. The final part of the book reviews the emerging applications of microcavity and microchannel plasmas, the synthesis and assembly of nanomaterials through plasma electrochemistry, the large-scale generation of ozone using microplasmas and novel applications of atmospheric-pressure non-thermal plasmas in dentistry. Going beyond the scope of traditional plasma texts, the presentation is very well suited for senior undergraduate, graduate students and postdoctoral researchers specializing in plasma physics.
Download or read book Metallic Glasses written by Behrooz Movahedi and published by BoD – Books on Demand. This book was released on 2016-08-17 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: Metallic glasses and amorphous materials have attracted much more attention in the last two decades. A noncrystalline solid produced by continuous cooling from the liquid state is known as a glass. From the other point of view, a noncrystalline material, obtained by any other process, for example, vapor deposition or solid-state processing methods such as mechanical alloying, but not directly from the liquid state, is referred to as an amorphous material. At this moment, bulk metallic glasses (BMG) are appearing as a new class of metallic materials with unique physical and mechanical properties for structural and functional usage. Extreme values of strength, fracture toughness, magnetic properties, corrosion resistance, and other properties have been registered in BMG materials.
