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Simulation Of Plasma Fluxes To Material Surfaces With Self Consistent Edge Turbulence And Transport For Tokamaks
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Book Synopsis Simulation of Plasma Fluxes to Material Surfaces with Self-Consistent Edge Turbulence and Transport for Tokamaks by :
Download or read book Simulation of Plasma Fluxes to Material Surfaces with Self-Consistent Edge Turbulence and Transport for Tokamaks written by and published by . This book was released on 2004 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: The edge-plasma profiles and fluxes to the divertor and walls of a divertor tokamak with a magnetic X-point are simulated by coupling a 2D transport code (UEDGE) and a 3D turbulence code (BOUT). An relaxed iterative coupling scheme is used where each code is run on its characteristic time scale, resulting in a statistical steady state. Plasma variables of density, parallel velocity, and separate ion and electron temperatures are included, together with a fluid neutral model for recycling neutrals at material surfaces. Results for the DIII-D tokamak parameters show that the turbulence is preferentially excited in the outer radial region of the edge where magnetic curvature is destabilizing and that substantial plasma particle flux is transported to the main chamber walls. These results are qualitatively consistent with some experimental observations. The coupled transport/turbulence simulation technique provides a strategy to understanding edge-plasma physics in more detailed than previously available and to significantly enhance the realism of predictions of the performance of future devices.
Download or read book Rickenbach - Das Dorf written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Washington Journal written by and published by . This book was released on with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt: Journal of a trip to a GAR encampment in Washington, DC. Very detailed description of his trip to the White House. Includes description of a day spent sight seeing in Cleveland, OH on the return trip to Michigan.
Book Synopsis Transport Simulations for Tokamak Edge-plasmas by :
Download or read book Transport Simulations for Tokamak Edge-plasmas written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The edge plasma plays key roles in tokamak devices: generates the edge transport-barrier yielding the L-H core confinement transition, distributes the core charged-particle energy to surrounding material surfaces, shields the core from impurities, and removes helium ash in fusion plasmas. The transport of density, momentum, and energy in the near-separatrix edge region, and the corresponding self-consistent electrostatic potential, require a two-dimensional description, here incorporated into the UEDGE code. In the direction across the B-field, both turbulent transport and classical cross-field flows are important. The role of classical flows is analyzed in detail in the presence of an assumed diffusive turbulent transport. Results and explanations are given for the generation of radial electric field near the separatrix, edge plasma asymmetries and differences between double-null DIII-D and NSTX devices, comparisons with DIII-D diagnostics for single-null divertor, and core/edge transport coupling.
Book Synopsis Turbulent Transport Modeling in the Edge Plasma of Tokamaks by : Clothilde Colin
Download or read book Turbulent Transport Modeling in the Edge Plasma of Tokamaks written by Clothilde Colin and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The possibility to produce power by using magnetically confined fusion is a scientific and technological challenge. The perspective of ITER conveys strong signals to intensify modeling effort on magnetized fusion plasmas. The success of the fusion operation is conditioned by the quality of plasma confinement in the core of the reactor and by the control of plasma exhaust on the wall. Both phenomena are related to turbulent cross-field transport that is at the heart of the notion of magnetic confinement studies, particle and heat losses. The study of edge phenomena is therefore complicated by a particularly complex magnetic geometry.This calls for an improvement of our capacity to develop numerical tools able to reproduce turbulent transport properties reliable to predict particle and energy fluxes on the plasma facing components. This thesis introduces the TOKAM3X fluid model to simulate edge plasma turbulence. A special focus is made on the code Verification and the Validation. It is a necessary step before using a code as a predictive tool. Then new insights on physical properties of the edge plasma turbulence are explored. In particular, the poloidal asymmetries induced by turbulence and observed experimentally in the Low-Field-Side of the devices are investigated in details. Great care is dedicated to the reproduction of the MISTRAL base case which consists in changing the magnetic configuration and observing the impact on parallel flows in the poloidal plane. The simulations recover experimental measurements and provide new insights on the effect of the plasma-wall contact position location on the turbulent features, which were not accessible in experiments.
Book Synopsis Development of a Fluid Code for Tokamak Edge Plasma Simulation. Investigation on Non-local Transport by : Hugo Bufferand
Download or read book Development of a Fluid Code for Tokamak Edge Plasma Simulation. Investigation on Non-local Transport written by Hugo Bufferand and published by . This book was released on 2012 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the scope of designing future nuclear fusion reactors, a clear understanding of the plasma-wall interaction is mandatory. Indeed, a predictive estimation of heat flux impacting the surface and the subsequent emission of impurities from the wall is necessary to ensure material integrity and energy confinement performances. In that perspective, the fluid code SolEdge2D has been developed to simulate plasma transport in the tokamak edge plasma. The plasma-wall interaction is modeled using an innovative penalization technique. This method enables in particular to take complex plasma facing components geometry into account. In parallel to this numerical effort, a theoretical work has been achieved to find appropriate corrections to fluid closures when collisionality drops. The study of stochastic 1D models has been realized in collaboration with physicists from the CSDC group in Florence. A generalized Fourier law taking long range spatio-temporal correlations has been found to properly account for ballistic transport in the low collisional regime. This formulation is expected to be used to model parallel heat flux or turbulent cross-field transport in tokamak plasmas.
Book Synopsis Kinetic Simulation of Edge Instability in Fusion Plasmas by : Daniel Patrick Fulton
Download or read book Kinetic Simulation of Edge Instability in Fusion Plasmas written by Daniel Patrick Fulton and published by . This book was released on 2015 with total page 103 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this work, gyrokinetic simulations in edge plasmas of both tokamaks and field reversed configurations (FRC) have been carried out using the Gyrokinetic Toroidal Code (GTC) and A New Code (ANC) has been formulated for cross-separatrix FRC simulation. In the tokamak edge, turbulent transport in the pedestal of an H-mode DIII-D plasma is studied via simulations of electrostatic driftwaves. Annulus geometry is used and simulations focus on two radial locations corresponding to the pedestal top with mild pressure gradient and steep pressure gradient. A reactive trapped electron instability with typical ballooning mode structure is excited in the pedestal top. At the steep gradient, the electrostatic instability exhibits unusual mode structure, peaking at poloidal angles theta=+- pi/2. Simulations find this unusual mode structure is due to steep pressure gradients in the pedestal but not due to the particular DIII-D magnetic geometry. Realistic DIII-D geometry has a stabilizing effect compared to a simple circular tokamak geometry. Driftwave instability in FRC is studied for the first time using gyrokinetic simulation. GTC is upgraded to treat realistic equilibrium calculated by an MHD equilibrium code. Electrostatic local simulations in outer closed flux surfaces find ion-scale modes are stable due to the large ion gyroradius and that electron drift-interchange modes are excited by electron temperature gradient and bad magnetic curvature. In the scrape-off layer (SOL) ion-scale modes are excited by density gradient and bad curvature. Collisions have weak effects on instabilities both in the core and SOL. Simulation results are consistent with density fluctuation measurements in the C-2 experiment using Doppler backscattering (DBS). The critical density gradients measured by the DBS qualitatively agree with the linear instability threshold calculated by GTC simulations. One outstanding critical issue in the FRC is the interplay between turbulence in the FRC core and SOL regions. While the magnetic flux coordinates used by GTC provide a number of computational advantages, they present unique challenges at the magnetic field separatrix. To address this limitation, a new code, capable of coupled core-SOL simulations, is formulated, implemented, and successfully verified.
Book Synopsis Understand and Predict the Power Threshold Leading to Reduced Turbulent Transport at the Edge of Tokamak Plasma by : Gregory De Dominici
Download or read book Understand and Predict the Power Threshold Leading to Reduced Turbulent Transport at the Edge of Tokamak Plasma written by Gregory De Dominici and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A model based on a model which natively contained turbulence and turbulence driven flow. It has been improved to include the diamagnetic effects, the magnetic fluctuations, and in this work, we study the parametric dependencies of the observed L-H transition power threshold with respect to the ion mass. By including the diamagnetic effects in our model, we allow the competition between the drift waves and the interchange instabilities. This competition is here studied using fixed gradient simulation. We show in this work that the diamagnetic effects are stabilizing for a resistivity close to experimental conditions. Electromagnetic effects lead to more unstable modes at realistic resistivities. Moreover, a quasilinear estimation of the turbulent flux is able to qualitatively grasp the competition between the drift waves and the interchange and the behaviour of the nonlinear electrostatic turbulent flux with resistivity and plasma beta. Another parametric dependency of the turbulence is studied, by changing the mass of the isotope. This is known as the isotope effect. We show here that the turbulence is reduced when the ion mass is increased. Finally, the characteristic times of the turbulence are studied.Magnetic fluctuations have a dramatic effect on correlation times of the turbulence, by drastically reducing them. Accounting for these results, we present in this work the auto-generation of a transport barrier with electromagnetic simulations of edge turbulence, when the heat power is higher than a threshold, using flux-driven simulations. We have then changed the isotope, and correspondingly to experiments, the power threshold is lower for higher isotope mass.
Book Synopsis Edge Plasma Modeling of Limiter Surfaces in a Tokamak Divertor Configuration by :
Download or read book Edge Plasma Modeling of Limiter Surfaces in a Tokamak Divertor Configuration written by and published by . This book was released on 1998 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt: During the startup phase of a tokamak the plasma configuration may evolve from a limiter to a divertor configuration. Some of the particle and heat flux from the core will be deposited on material surfaces near the separatrix instead of the divertor plates. Examples of such surfaces include the center-post in most tokamaks, baffles near the x-point that create closed divertors, and outboard limiter surfaces. Two-dimensional edge plasma models for tokamak divertor configurations typically give detailed information about the particle and heat fluxes on the divertor plates, but yield little or no information about fluxes on these other localized surfaces near the core plasma. To realistically model the startup phase of a tokamak it is necessary to compute the plasma interaction with both limiter and divertor surfaces. The UEDGE code [l] has been modified to include these limiter surfaces. In this report we present simulation results for an idealized ITER [2] startup configuration with variations in the limiter penetration depth and surface shape.
Book Synopsis Modeling the Turbulent Momentum Transport in Tokamak Plasmas by : Pierre Cottier
Download or read book Modeling the Turbulent Momentum Transport in Tokamak Plasmas written by Pierre Cottier and published by LAP Lambert Academic Publishing. This book was released on 2014-04-01 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt: The magnetic confinement in tokamaks is for now the most advanced way towards energy production by nuclear fusion. Both theoretical and experimental studies showed that rotation generation can increase its performance by reducing the turbulent transport in tokamak plasmas. The rotation influence on the heat and particle fluxes is studied along with the angular momentum transport with the quasi-linear gyro-kinetic eigenvalue code QuaLiKiz. For this purpose, the QuaLiKiz code is modified in order to take the plasma rotation into account and compute the angular momentum flux. It is shown that QuaLiKiz framework is able to correctly predict the angular momentum flux including the ExB shear induced residual stress as well as the influence of rotation on the heat and particle fluxes. The different contributions to the turbulent momentum flux are studied and successfully compared against both non-linear gyro-kinetic simulations and experimental data.
Book Synopsis Simulation of Edge-plasma Profiles and Turbulence Related to L-H Transitions in Tokamaks by :
Download or read book Simulation of Edge-plasma Profiles and Turbulence Related to L-H Transitions in Tokamaks written by and published by . This book was released on 1999 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Understanding plasma profile evolution and plasma turbulence are two important aspects of developing a predictive model for edge-plasma in tokamaks and other fusion-related devices. Here they describe results relevant to the L-H transition phenomena observed in tokamaks obtained from two simulations codes which emphasize the two aspects of the problem. UEDGE solves for the two-dimensional (2-D) profiles of a multi-species plasma and neutrals given some anomalous cross-field diffusion coefficients, and BOUT solves for the three-dimensional (3-D) turbulence that gives rise to the anomalous diffusion. These two codes are thus complementary in solving different aspects of the edge-plasma transport problem; ultimately, they want to couple the codes so that UEDGE uses BOUT's turbulence transport results, and BOUT uses UEDGE's plasma profiles with a fully automated iteration procedure. This goal is beyond the present paper; here they show how each aspect of the problem, i.e., profiles and turbulent transport, can contribute to L-H type transitions.
Book Synopsis Turbulence and Transport in Enhanced Confinement Regimes of Tokamaks by :
Download or read book Turbulence and Transport in Enhanced Confinement Regimes of Tokamaks written by and published by . This book was released on 1996 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Theory of Tokamak Plasmas by : R.B. White
Download or read book Theory of Tokamak Plasmas written by R.B. White and published by Elsevier. This book was released on 2017-01-31 with total page 374 pages. Available in PDF, EPUB and Kindle. Book excerpt: This is a graduate textbook on tokamak physics, designed to provide a basic introduction to plasma equilibrium, particle orbits, transport, and those ideal and resistive magnetohydrodynamic instabilities which dominate the behavior of a tokamak discharge, and to develop the mathematical methods necessary for their theoretical analysis.
Book Synopsis Numerical Modelling of Transport and Turbulence in Tokamak Edge Plasma with Divertor Configuration by : Davide Galassi
Download or read book Numerical Modelling of Transport and Turbulence in Tokamak Edge Plasma with Divertor Configuration written by Davide Galassi and published by . This book was released on 2017 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nuclear fusion could offer a new source of stable, non-CO2 emitting energy. Today, tokamaks offer the best performance by confining a high temperature plasma by means of a magnetic field. Two of the major technological challenges for the operation of tokamaks are the power extraction and the confinement of plasma over long periods. These issues are associated with the transport of particles and heat, which is determined by turbulence, from the central plasma to the edge zone. In this thesis, we model turbulence in the edge plasma. We study in particular the divertor configuration, in which the central plasma is isolated from the walls by means of an additional magnetic field. This complex magnetic geometry is simulated with the fluid turbulence code TOKAM3X, developed in collaboration between the IRFM at CEA and the M2P2 laboratory of the University of Aix-Marseille.A comparison with simulations in simplified geometry shows a similar intermittent nature of turbulence. Nevertheless, the amplitude of the fluctuations, which has a maximum at the equatorial plane, is greatly reduced near the X-point, where the field lines become purely toroidal, in agreement with the recent experimental data. The simulations in divertor configuration show a significantly higher confinement than in circular geometry. A partial inhibition of the radial transport of particles at the X-point contributes to this improvement. This mechanism is potentially important for understanding the transition from low confinement mode to high confinement mode, the intended operational mode for ITER.
Book Synopsis Magnetic Fusion Energy by : George Neilson
Download or read book Magnetic Fusion Energy written by George Neilson and published by Woodhead Publishing. This book was released on 2016-06-02 with total page 634 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic Fusion Energy: From Experiments to Power Plants is a timely exploration of the field, giving readers an understanding of the experiments that brought us to the threshold of the ITER era, as well as the physics and technology research needed to take us beyond ITER to commercial fusion power plants. With the start of ITER construction, the world’s magnetic fusion energy (MFE) enterprise has begun a new era. The ITER scientific and technical (S&T) basis is the result of research on many fusion plasma physics experiments over a period of decades. Besides ITER, the scope of fusion research must be broadened to create the S&T basis for practical fusion power plants, systems that will continuously convert the energy released from a burning plasma to usable electricity, operating for years with only occasional interruptions for scheduled maintenance. Provides researchers in academia and industry with an authoritative overview of the significant fusion energy experiments Considers the pathway towards future development of magnetic fusion energy power plants Contains experts contributions from editors and others who are well known in the field
Book Synopsis Plasma Surface Interactions in Controlled Fusion Devices by :
Download or read book Plasma Surface Interactions in Controlled Fusion Devices written by and published by . This book was released on 1978 with total page 658 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Material Migration in Tokamak Plasmas with a Three-dimensional Boundary by : Ruth Laengner
Download or read book Material Migration in Tokamak Plasmas with a Three-dimensional Boundary written by Ruth Laengner and published by Forschungszentrum Jülich. This book was released on 2013 with total page 175 pages. Available in PDF, EPUB and Kindle. Book excerpt:
