The Quasi-coherent Signature of Enhanced D Alpha H-mode in Alcator C-Mod PDF Download
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Author: Joseph Allan Snipes
Publisher:
ISBN:
Category :
Languages : en
Pages : 10
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Book Description
The steady-state H-mode regime found at moderate to high density in Alcator C-Mod, known as Enhanced D alpha H-mode (EDA), appears to be maintained by a continuous quasi-coherent (QC) mode in the edge steep gradient region. Large amplitude density and magnetic fluctuations with typical frequencies of %7E100 kHz are driven by the QC mode. These fluctuations are measured in the steep edge gradient region by inserting a fast scanning probe containing two poloidally separated Langmuir probes and a poloidal field pick-up coil. As the probe approaches the plasma edge, clear magnetic fluctuations were measured within %7E 2 cm of the last closed flux surface (LCFS). The mode amplitude falls off rapidly with distance from the plasma center with an exponential decay length of kr approximately equal to 1.5 cm-1, measured 10 cm above the outboard midplane. The root-mean-square amplitude of the poloidal field fluctuation extrapolated to the LCFS was approximately 5 G. The density fluctuations, on the other hand, were visible on the Langmuir probe only when it was within a few mm of the LCFS. The potential and density fluctuations were sufficiently in phase to enhance particle transport at the QC mode frequency. These results show that the quasi-coherent signature of the EDA H-mode is an electromagnetic mode that appears to be responsible for the enhanced particle transport in the plasma edge.
Author: Joseph Allan Snipes
Publisher:
ISBN:
Category :
Languages : en
Pages : 10
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Book Description
The steady-state H-mode regime found at moderate to high density in Alcator C-Mod, known as Enhanced D alpha H-mode (EDA), appears to be maintained by a continuous quasi-coherent (QC) mode in the edge steep gradient region. Large amplitude density and magnetic fluctuations with typical frequencies of %7E100 kHz are driven by the QC mode. These fluctuations are measured in the steep edge gradient region by inserting a fast scanning probe containing two poloidally separated Langmuir probes and a poloidal field pick-up coil. As the probe approaches the plasma edge, clear magnetic fluctuations were measured within %7E 2 cm of the last closed flux surface (LCFS). The mode amplitude falls off rapidly with distance from the plasma center with an exponential decay length of kr approximately equal to 1.5 cm-1, measured 10 cm above the outboard midplane. The root-mean-square amplitude of the poloidal field fluctuation extrapolated to the LCFS was approximately 5 G. The density fluctuations, on the other hand, were visible on the Langmuir probe only when it was within a few mm of the LCFS. The potential and density fluctuations were sufficiently in phase to enhance particle transport at the QC mode frequency. These results show that the quasi-coherent signature of the EDA H-mode is an electromagnetic mode that appears to be responsible for the enhanced particle transport in the plasma edge.
Author:
Publisher:
ISBN:
Category : Fusion reactors
Languages : en
Pages : 890
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Book Description
Author: Thomas J. Dolan
Publisher: Springer Science & Business Media
ISBN: 1447155564
Category : Technology & Engineering
Languages : en
Pages : 816
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Book Description
Magnetic Fusion Technology describes the technologies that are required for successful development of nuclear fusion power plants using strong magnetic fields. These technologies include: • magnet systems, • plasma heating systems, • control systems, • energy conversion systems, • advanced materials development, • vacuum systems, • cryogenic systems, • plasma diagnostics, • safety systems, and • power plant design studies. Magnetic Fusion Technology will be useful to students and to specialists working in energy research.
Author: Kimitaka Itoh
Publisher: CRC Press
ISBN: 9780750304498
Category : Plasma dynamics
Languages : en
Pages : 0
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Book Description
This monograph, the latest in the IOP Plasma Physics Series, written by three of the most senior and internationally respected Japanese fusion scientists, presents a self-consistent picture of turbulent transport, structural formation and transitions-processes that are typical of the physics of many far from equilibrium systems such as exist in magnetically confined and inhomogeneous plasmas. The Author's view is that the plasma structure, fluctuations and turbulent transport are continually regulating each other and, in addition, that the structural formation and structural transition of plasmas are typical of the physics of far from equilibrium systems. The book presents and explains why the plasma inhomogeneity is the ordering parameter governing transport and how self-sustained fluctuations can be driven through subcritical excitation even beyond linear stability. In addition, the authors derive the non-linear gradient-flux relation with the result that asymmetry arising from the fluctuations allows mixing of the various kinds of fluxes. This emphasises the ever important role that electromagnetic fields play in inducing long range interactions, couplings and bifurcations in plasmas. To illustrate, a transport simulation of a high temperature current fusion experiment like JET-the Joint European Torus-helps us to understand various structural formations such as the H-mode. With the insight that structural formation in high temperature plasmas is fundamental to an accurate description of the basic phenomena that occur in our present cosmos, the authors provide a comprehensive account of the subject to help fusion researchers, fluid dynamicists and astrophysicists alike. The book addresses a key to understanding the age old question of what has occurred in the early stage of the our universe and what is likely to occur in the final stage of our universe.
Author: C.M. Braams
Publisher: CRC Press
ISBN: 9781420033786
Category : Science
Languages : en
Pages : 352
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Book Description
Fusion research started over half a century ago. Although the task remains unfinished, the end of the road could be in sight if society makes the right decisions. Nuclear Fusion: Half a Century of Magnetic Confinement Fusion Research is a careful, scholarly account of the course of fusion energy research over the past fifty years. The authors outline the different paths followed by fusion research from initial ignorance to present understanding. They explore why a particular scheme would not work and why it was more profitable to concentrate on the mainstream tokamak development. The book features descriptive sections, in-depth explanations of certain physical and technical issues, scientific terms, and an extensive glossary that explains relevant abbreviations and acronyms.
Author: A.V. Melnikov
Publisher: Springer
ISBN: 303003481X
Category : Science
Languages : en
Pages : 253
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Book Description
This work introduces heavy ion beam probe diagnostics and presents an overview of its applications. The heavy ion beam probe is a unique tool for the measurement of potential in the plasma core in order to understand the role of the electric field in plasma confinement, including the mechanism of transition from low to high confinement regimes (L–H transition). This allows measurement of the steady-state profile of the plasma potential, and its use has been extended to include the measurement of quasi-monochromatic and broadband oscillating components, the turbulent-particle flux and oscillations of the electron density and poloidal magnetic field. Special emphasis is placed on the study of Geodesic Acoustic Modes and Alfvén Eigenmodes excited by energetic particles with experimental data sets. These experimental studies help to understand the link between broadband turbulent physics and quasi-coherent oscillations in devices with a rather different magnetic configuration. The book also compares spontaneous and biased transitions from low to high confinement regimes on both classes of closed magnetic traps (tokamak and stellarator) and highlights the common features in the behavior of electric potential and turbulence of magnetized plasmas. A valuable resource for physicists, postgraduates and students specializing in plasma physics and controlled fusion.
Author: C Wendell Horton, Jr
Publisher: World Scientific
ISBN: 9814678686
Category : Science
Languages : en
Pages : 248
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Book Description
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.
Author: Kenrō Miyamoto
Publisher:
ISBN: 9784900491113
Category : Controlled fusion
Languages : en
Pages : 401
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Book Description
Author: L. J. Reinders
Publisher: Springer Nature
ISBN: 3030643441
Category : Science
Languages : en
Pages : 628
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Book Description
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.
Author: Kenrō Miyamoto
Publisher:
ISBN:
Category : Controlled fusion
Languages : en
Pages : 296
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Book Description
