Magnetic Stochasticity in Gyrokinetic Simulations of Plasma Microturbulence PDF Download
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Languages : en
Pages : 6
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Author:
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Category :
Languages : en
Pages : 6
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Author: Sadrilla Abdullaev
Publisher: Springer Science & Business Media
ISBN: 3319018906
Category : Science
Languages : en
Pages : 422
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Book Description
This is the first book to systematically consider the modern aspects of chaotic dynamics of magnetic field lines and charged particles in magnetically confined fusion plasmas. The analytical models describing the generic features of equilibrium magnetic fields and magnetic perturbations in modern fusion devices are presented. It describes mathematical and physical aspects of onset of chaos, generic properties of the structure of stochastic magnetic fields, transport of charged particles in tokamaks induced by magnetic perturbations, new aspects of particle turbulent transport, etc. The presentation is based on the classical and new unique mathematical tools of Hamiltonian dynamics, like the action--angle formalism, classical perturbation theory, canonical transformations of variables, symplectic mappings, the Poincaré-Melnikov integrals. They are extensively used for analytical studies as well as for numerical simulations of magnetic field lines, particle dynamics, their spatial structures and statistical properties. The numerous references to articles on the latest development in the area are provided. The book is intended for graduate students and researchers who interested in the modern problems of magnetic stochasticity in magnetically confined fusion plasmas. It is also useful for physicists and mathematicians interested in new methods of Hamiltonian dynamics and their applications.
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Category :
Languages : en
Pages :
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Gyrokinetics is the description of low-frequency dynamics in magnetized plasmas. In magnetic-confinement fusion, it provides the most fundamental basis for numerical simulations of microturbulence; there are astrophysical applications as well. In this tutorial, a sketch of the derivation of the novel dynamical system comprising the nonlinear gyrokinetic (GK) equation (GKE) and the coupled electrostatic GK Poisson equation will be given by using modern Lagrangian and Lie perturbation methods. No background in plasma physics is required in order to appreciate the logical development. The GKE describes the evolution of an ensemble of gyrocenters moving in a weakly inhomogeneous background magnetic field and in the presence of electromagnetic perturbations with wavelength of the order of the ion gyroradius. Gyrocenters move with effective drifts, which may be obtained by an averaging procedure that systematically, order by order, removes gyrophase dependence. To that end, the use of the Lagrangian differential one-form as well as the content and advantages of Lie perturbation theory will be explained. The electromagnetic fields follow via Maxwell's equations from the charge and current density of the particles. Particle and gyrocenter densities differ by an important polarization effect. That is calculated formally by a "pull-back" (a concept from differential geometry) of the gyrocenter distribution to the laboratory coordinate system. A natural truncation then leads to the closed GK dynamical system. Important properties such as GK energy conservation and fluctuation noise will be mentioned briefly, as will the possibility (and diffculties) of deriving nonlinear gyro fluid equations suitable for rapid numerical solution -- although it is probably best to directly simulate the GKE. By the end of the tutorial, students should appreciate the GKE as an extremely powerful tool and will be prepared for later lectures describing its applications to physical problems.
Author: Boris Galperin
Publisher: Cambridge University Press
ISBN: 1108577296
Category : Science
Languages : en
Pages : 527
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Book Description
In recent decades, great progress has been made in our understanding of zonal jets across many subjects - atmospheric science, oceanography, planetary science, geophysical fluid dynamics, plasma physics, magnetohydrodynamics, turbulence theory - but communication between researchers from different fields has been weak or non-existent. Even the terminology in different fields may be so disparate that researchers working on similar problems do not understand each other. This comprehensive, multidisciplinary volume will break cross-disciplinary barriers and aid the advancement of the subject. It presents a state-of-the-art summary of all relevant branches of the physics of zonal jets, from the leading experts. The phenomena and concepts are introduced at a level accessible to beginning graduate students and researchers from different fields. The book also includes a very extensive bibliography.
Author: Gabriele Merlo
Publisher:
ISBN:
Category :
Languages : en
Pages : 227
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Book Description
Mots-clés de l'auteur: plasma ; fusion ; tokamak ; turbulence ; gyrokinetic simulations ; plasma shaping ; Zonal Flows ; Geodesic Acoustic Mode.
Author: W. M. Tang
Publisher:
ISBN:
Category : Kinetic theory of gases
Languages : en
Pages : 32
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Book Description
Author: Moritz Johannes Püschel
Publisher:
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Category :
Languages : de
Pages : 174
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Author: Jerome L. V. Lewandowski
Publisher:
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Category : Dynamics of a particle
Languages : en
Pages : 8
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Author: W. W. Lee
Publisher:
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Category : Computer simulation
Languages : en
Pages : 12
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Author: Paul Crandall
Publisher:
ISBN:
Category :
Languages : en
Pages : 229
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Book Description
One of the most challenging problems facing plasma physicists today involves the modeling of plasma turbulence and transport in magnetic confinement experiments. The most successful model to this end so far is the reduced gyrokinetic model. Such a model cannot be solved analytically, but can be used to simulate the plasma behavior and transport with the help of present-day supercomputers. This has lead to the development of many different codes which simulate the plasma using the gyrokinetic model in various ways. These models have achieved a large amount of success in describing the core of the plasma for conventional tokamak devices. However, numerous difficulties have been encountered when applying these models to more extreme parameter regimes, such as the edge and scrape-off layer of the tokamak, and high plasma devices, such as spherical tokamaks. The development and application of the gyrokinetic model (specifically with the gyrokinetic code, GENE) to these more extreme parameter ranges shall be the focus of this thesis. One of the main accomplishments during this thesis project is the development of a more advanced collision operator suitable for studying the low temperature plasma edge. The previous collision operator implemented in the code was found to artificially create free energy at high collisionality, leading to numerical instabilities when one attempted to model the plasma edge. This made such an analysis infeasible. The newly implemented collision operator conserves particles, momentum, and energy to machine precision, and is guaranteed to dissipate free energy, even in a nonisothermal scenario. Additional finite Larmor radius correction terms have also been implemented in the local code, and the global code version of the collision operator has been adapted for use with an advanced block-structured grid scheme, allowing for more affordable collisional simulations. The GENE code, along with the newly implemented collision operator developed in this thesis, has been applied to study plasma turbulence and transport in the edge (tor = 0:9) of an L-mode magnetic confinement discharge of ASDEX Upgrade. It has been found that the primary microinstabilities at that radial position are electron drift waves destabilized by collisions and electromagnetic effects. At low toroidal mode numbers, ion temperature gradient driven modes and microtearing modes also seem to exist. In nonlinear simulations with the nominal experimental parameters, the simulated electron heat flux was four times higher than the experimental reconstruction, and the simulated ion heat flux was twice as high. However, both the ion and electron simulated heat flux could be brought into agreement with experimental values by lowering the input logarithmic electron temperature gradient by 40%. It was also found that the cross-phases between the electrostatic potential and the moments agreed well for the part of the binormal spectrum where the dominant transport occurred, and was fairly poor at larger scales where minimal transport occurred. Finally, a new scheme for evaluating the electromagnetic fields has been developed to address the instabilities occurring in nonlinear local and global gyrokinetic simulations at high plasma . This new scheme is based on evaluating the electromagnetic induction explicitly, and constructing the gyrokinetic equation based on the original distribution, rather than the modified distribution which implicitly takes into account the induction. This new scheme removes the artificial instability occurring in global simulations, enabling the study of high scenarios with GENE. The new electromagnetic scheme can also be generalized to a full-f implementation, however, it would require updating the field matrix every time-step to avoid the cancellation problem. The new scheme (including the parallel nonlinearity) does not remove the local instability, suggesting that that instability (caused by magnetic field perturbations shorting out zonal flows) is part of the physics of the local model.
