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Author : Nicolas Christen
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (129 download)
Download or read book Bistable Turbulent Transport in Fusion Plasmas with Rotational Shear written by Nicolas Christen and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : C Wendell Horton, Jr
Publisher : #N/A
ISBN 13 : 9813225904
Total Pages : 522 pages
Book Rating : 4.8/5 (132 download)
Download or read book Turbulent Transport In Magnetized Plasmas (Second Edition) written by C Wendell Horton, Jr and published by #N/A. This book was released on 2017-07-21 with total page 522 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Author : C. Hidalgo
Publisher :
ISBN 13 :
Total Pages : 9 pages
Book Rating : 4.:/5 (316 download)
Download or read book Statistical Description of Turbulent Transport in Fusion Plasmas written by C. Hidalgo and published by . This book was released on 2004* with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Radu Balescu
Publisher : CRC Press
ISBN 13 : 9781420034684
Total Pages : 498 pages
Book Rating : 4.0/5 (346 download)
Download or read book Aspects of Anomalous Transport in Plasmas written by Radu Balescu and published by CRC Press. This book was released on 2005-04-01 with total page 498 pages. Available in PDF, EPUB and Kindle. Book excerpt: Anomalous transport is a ubiquitous phenomenon in astrophysical, geophysical and laboratory plasmas; and is a key topic in controlled nuclear fusion research. Despite its fundamental importance and ongoing research interest, a full understanding of anomalous transport in plasmas is still incomplete, due to the complexity of the nonlinear phenomena involved. Aspects in Anomalous Transport in Plasmas is the first book to systematically consider anomalous plasma transport theory and provides a unification of the many theoretical models by emphasizing interrelations between seemingly different methodologies. It is not intended as a catalogue of the vast number of plasma instabilities leading to anomalous transport; instead it chooses a number of these and emphasizes the aspects specifically due to turbulence. After a brief introduction, the microscopic theory of turbulence is discussed, including quasilinear theory and various aspects of renormalization methods, which leads to an understanding of resonance broadening, mode coupling, trajectory correlation and clumps. The second half of the book is devoted to stochiastic tramsport, using methods based on the Langevin equations and on Random Walk theory. This treatment aims at going beyond the traditional limits of weak turbulence, by introducing the recently developed method of decorrelation trajectories, and its application to electrostatic turbulence, magnetic turbulence and zonal flow generation. The final chapter includes very recent work on the nonlocal transport phenomenon.
Author : Benkadda Sadruddin
Publisher : World Scientific
ISBN 13 : 9814547743
Total Pages : 460 pages
Book Rating : 4.8/5 (145 download)
Download or read book Transport, Chaos And Plasma Physics 2 written by Benkadda Sadruddin and published by World Scientific. This book was released on 1996-08-22 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt: Since the early developments of 'nonlinear science', plasma physics played a major role in its evolution: solitons, hamiltonian chaos, distinction between absolute and convective instabilities, and dynamics of coherent structures in turbulence. Understanding transport in plasmas is important for fusion devices but also for fundamental astrophysics, for fluid mechanics, for theoretical chemistry and engineering, and plasma processing in engineering.This second workshop gathered experts in plasma physics, nonlinear phenomena and mathematics. It aimed at enabling theoreticians, numericians and experimentalists in plasma turbulence to relate electromagnetic fluctuations, modes of self-organisation and transport processes. It may lead to developing new diagnostics and new methods for signal processing.
Author : Xin Wang
Publisher :
ISBN 13 :
Total Pages : 171 pages
Book Rating : 4.:/5 (15 download)
Download or read book Turbulent Particle Transport in H-Mode Plasmas on Diii-D written by Xin Wang and published by . This book was released on 2016 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: Particle transport is an important topic in plasma physics. It determines the density profile of a burning plasma within a tokamak a magnetic confinement device. Microscopic turbulent particle transport is two orders of magnitude larger than other transport mechanisms for electrons and small ions. In order to confine a plasma in a tokamak with a core density that exceeds the fusion criteria, it is essential to study turbulent particle transport. This thesis investigates how different plasma parameters such as the toroidal rotation and microscopic instabilities affect turbulent particle transport in the DIII-D tokamak. First, we show how toroidal rotation can indirectly affect particle transport, through its contribution to the radial electric field and thus the E B shearing rate. The plasma discharge which has best confinement is the one whose E B shearing rate is larger than or at least similar to the growth rates that drive turbulent transport at the plasma edge. Second, for the first time on DIII-D, we observe a correlation between electron density gradient and instability mode frequency in the plasma core. We find that, when the turbulence is driven by the ion temperature gradient (ITG), the local density gradient increases as the the absolute frequency of the dominant unstable mode decreases. Once the dominant unstable mode switches over to the trapped electron mode (TEM) regime, the local density gradient decreases again. As a result the density gradient reaches a maximum when the mode has zero frequency, which is corresponds to the cross over from ITG to TEM. This correlation opens a new opportunity for future large burning plasma devices such as ITER to increase the core density by controlling the turbulence regime. Finally, we show that, in low density regime, a reduction in core density is observed when electron cyclotron heating (ECH) is applied. This reduction is not the result of a change in turbulence regime nor the result of a change in the density gradient in the core. Through detailed time-dependent experimental analysis, linear gyro-kinetic simulations, and comparison to turbulence measurements we show that this reduction in core density is the result of an increase in turbulence drive at the plasma edge.
Author : Claudia Norscini
Publisher :
ISBN 13 :
Total Pages : 154 pages
Book Rating : 4.:/5 (965 download)
Download or read book Self-organized Turbulent Transport in Fusion Plasmas written by Claudia Norscini and published by . This book was released on 2015 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt: Transport barriers (TB) are a key element in controlling turbulent transport and achieving high performance burning plasmas. Theoretical studies are addressing the turbulence self-regulation as a possible explanation for transport barrier formation but a complete understanding of such complex dynamics is still missing. In this context, we address self-organized turbulent transport in fusion plasmas with the aim of presenting a novel understanding of transport barriers dynamics. The numerical tools we use span simulations from the most complex gyrokinetic turbulence to simpler 2D fluid turbulence and predator-prey like models.Two features of self-organizations, avalanches and zonal flows (ZFs), appear to control large scale transport. In the SOL (Scrape Off Layer) , intermittent avalanche events do not allow for time or space scale separation between mean fields and fluctuation terms. In the edge, the generation of long living double shear layers in the profiles of the velocity reduces radial turbulent transport. Such radially distributed barriers govern profile corrugations. A 2D turbulent model for pedestal generation, which is not specific of Tokamak plasmas, has been developed, the pedestal being localized at the interface between regions with different zonal flow damping: the edge region, where zonal flows are weakly damped by collisions, and the SOL region characterized by zonal flow damping due to boundary conditions. Quasi-periodic relaxation events are studied reducing the model to three modes coupling to identify the interplay between streamers and ZFs and the role of Reynolds stress in the generation and saturation of TBs.
Author : Ilya Prigogine
Publisher : Springer Science & Business Media
ISBN 13 : 9780883189238
Total Pages : 480 pages
Book Rating : 4.1/5 (892 download)
Download or read book Chaotic Dynamics and Transport in Fluids and Plasmas written by Ilya Prigogine and published by Springer Science & Business Media. This book was released on 1992-10-31 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: Market: Students and researchers in chaos, plasma physics, and fluid transport. This superb collection of invited papers offers an excellent overview of the current status and future trends in chaotic dynamics, plasma and fluid physics, nonlinear phenomena and chaos, and transport and turbulence studies.
Author : Kimitaka Itoh
Publisher : CRC Press
ISBN 13 : 9780750304498
Total Pages : 0 pages
Book Rating : 4.3/5 (44 download)
Download or read book Transport and Structural Formation in Plasmas, written by Kimitaka Itoh and published by CRC Press. This book was released on 1999-01-01 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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 : Paola Mantica
Publisher :
ISBN 13 :
Total Pages : 22 pages
Book Rating : 4.:/5 (316 download)
Download or read book Perturbative Studies of Turbulent Transport in Fusion Plasmas written by Paola Mantica and published by . This book was released on 2006 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Juhyung Kim
Publisher :
ISBN 13 :
Total Pages : 354 pages
Book Rating : 4.:/5 (272 download)
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.
Author :
Publisher :
ISBN 13 :
Total Pages : 342 pages
Book Rating : 4.:/5 (113 download)
Download or read book Turbulent Transport in Fusion Plasmas written by and published by . This book was released on 2008 with total page 342 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author :
Publisher :
ISBN 13 :
Total Pages : 73 pages
Book Rating : 4.:/5 (982 download)
Download or read book Numerical and Experimental Investigation of Turbulent Transport Control Via Shaping of Radial Plasma Flow Profiles written by and published by . This book was released on 2017 with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulence, and turbulence-driven transport are ubiquitous in magnetically confined plasmas, where there is an intimate relationship between turbulence, transport, instability driving mechanisms (such as gradients), plasma flows, and flow shear. Though many of the detailed physics of the interrelationship between turbulence, transport, drive mechanisms, and flow remain unclear, there have been many demonstrations that transport and/or turbulence can be suppressed or reduced via manipulations of plasma flow profiles. This is well known in magnetic fusion plasmas [e.g., high confinement mode (H-mode) and internal transport barriers (ITB's)], and has also been demonstrated in laboratory plasmas. However, it may be that the levels of particle transport obtained in such cases [e.g. H-mode, ITB's] are actually lower than is desirable for a practical fusion device. Ideally, one would be able to actively feedback control the turbulent transport, via manipulation of the flow profiles. The purpose of this research was to investigate the feasibility of using both advanced model-based control algorithms, as well as non-model-based algorithms, to control cross-field turbulence-driven particle transport through appropriate manipulation of radial plasma flow profiles. The University of New Mexico was responsible for the experimental portion of the project, while our collaborators at the University of Montana provided plasma transport modeling, and collaborators at Lehigh University developed and explored control methods.
Author :
Publisher :
ISBN 13 :
Total Pages : 439 pages
Book Rating : 4.:/5 (727 download)
Download or read book Steady State Turbulent Transport in Magnetic Fusion Plasmas written by and published by . This book was released on 2007 with total page 439 pages. Available in PDF, EPUB and Kindle. Book excerpt: For more than a decade, the study of microturbulence, driven by ion temperature gradient (ITG) drift instabilities in tokamak devices, has been an active area of research in magnetic fusion science for both experimentalists and theorists alike. One of the important impetus for this avenue of research was the discovery of the radial streamers associated the ITG modes in the early nineties using a Particle-In-Cell (PIC) code. Since then, ITG simulations based on the codes with increasing realism have become possible with the dramatic increase in computing power. The notable examples were the demonstration of the importance of nonlinearly generated zonal flows in regulating ion thermal transport and the transition from Bohm to GyroBoham scaling with increased device size. In this paper, we will describe another interesting nonlinear physical process associated with the parallel acceleration of the ions, that is found to play an important role for the steady state turbulent transport. Its discovery is again through the use of the modern massively parallel supercomputers.
Author :
Publisher :
ISBN 13 :
Total Pages : 11 pages
Book Rating : 4.:/5 (685 download)
Download or read book Nonlinear Phenomena, Turbulence and Anomalous Transport in Fusion Plasmas written by and published by . This book was released on 1995 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: The nonlinear nature of the plasma turbulence, as measured by bicoherence analysis, has been studied in stellarator (ATF and W7AS) and tokamak (PBXM) devices. In ATF, little nonlinear interaction is found in the scrape-off layer region whereas the strength of the coupling is enhanced in the edge plasma region where the level of fluctuations is consistent with the theoretical expectations from resistive interchange modes. In W7AS the level of bicoherence is significantly smaller than in ATF. The comparison ATF/W7AS/PBXM suggest the important role of the magnetic shear to determine nonlinear behavior of the turbulence. The level of bicoherence also depends on the plasma conditions: in particular, it increases at the H-mode transition. The comparison between the nonlinear behavior of the turbulence in tokamaks and stellarators allows experimental verification of theoretical turbulence models.
Author : Shu Zhou
Publisher :
ISBN 13 : 9781267075536
Total Pages : 176 pages
Book Rating : 4.0/5 (755 download)
Download or read book Turbulent Transport of Energetic Ions and Thermal Plasmas written by Shu Zhou and published by . This book was released on 2011 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: Three experiments are conducted to study the effect of the turbulent waves on the transport of fast ions and thermal plasmas. In the first experiment, strong drift wave turbulence with linear geometry is observed in the Large Plasma Device (LAPD) on density gradients produced by a plate limiter. Energetic lithium ions orbit through the turbulent region. Scans with a collimated ion analyzer and with Langmuir probes give detailed profiles of the fast ion spatial distribution and the fluctuating fields. The fast-ion transport decreases rapidly with increasing fast-ion gyroradius. Unlike the diffusive transport caused by Coulomb collisions, in this case the turbulent transport is super-diffusive. Analysis and simulation suggest that such super-diffusive transport is due to the interaction of the fast ions with the low-frequency two-dimensional electrostatic turbulence. The second experiment studies the dependence of the fast ion transport on the nature of the turbulent waves. Strong turbulent waves with cylindrical geometry are observed in the LAPD on density gradients produced by an annular obstacle. The characteristics of the fluctuations are modified by changing the plasma species from helium to neon, and by modifying the bias on the obstacle. Different spatial structure sizes and correlation lengths (Lcorr) of the wave potential fields alter the fast ion transport. The effects of electrostatic fluctuations are reduced due to gyro-averaging, which explains the difference in the fast-ion transport. A transition from super-diffusive to sub-diffusive transport is observed when the fast ion interacts with the waves for most of a wave period, which agrees with theoretical predictions. The transport of thermal plasmas under electrostatic waves is explored in the third experiment. Sheared azimuthal flow is driven at the edge of a magnetized plasma cylinder through edge biasing. Strong fluctuations of density and potential are observed at the plasma edge, accompanied by large density gradient. Edge turbulence and cross-field transport are modified by changing the bias voltage on the obstacle and the axial magnetic field strength. In cases with low V bias and large Bz, improved plasma confinement is observed, along with steeper edge density gradients. The radially sheared flow induced by E x B dramatically changes the cross-phase between density and potential fluctuations, which causes the wave-induced particle flux to reverse its direction across the shear layer and forms a transport barrier. In cases with higher bias voltage or smaller Bz large radial transport and rapid depletion of the central plasma density are observed. Two-dimensional cross-correlation measurement shows that a mode with azimuthal mode number m=1 and large radial correlation length dominates the outward transport in these cases. Linear analysis based on a two-fluid Braginskii model suggests that the fluctuations are driven by both density gradient and flow shear at the plasma edge.
Download or read book Numerical and Theoretical Studies of Turbulence and Transport with E X B Shear Flows written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper reports: (1) substantial transport reduction by turbulence-driven E x B flows observed in 3D nonlinear gyrokinetic simulations of microturbulence in magnetically-confined toroidal plasmas; (2) analytical derivation of the effective shearing rate for the time-dependent E x B flow; (3) interpretation of experimental data using linear gyrokinetic microinstability rotation models of E x B shear; and (4) other developments in gyrokinetic theory and simulation.
