Particle Transport as a Result of Resonant Magnetic Perturbations

Particle Transport as a Result of Resonant Magnetic Perturbations
Author: Saskia Mordijck
Publisher:
Total Pages: 97
Release: 2011
Genre:
ISBN: 9781124408507

This thesis makes contributes to field of plasma physics with a particular focus on particle transport as a result of resonant magnetic perturbations (RPMs) in magnetic confinement devices (Tokamaks). RPMs have proven to be a useful technique to suppress edge localized modes (ELMs) that under certain conditions can damage the confinement device. In order to suppress ELMs, these magnetic perturbations are created to be be resonant at the edge of the plasma (i.e., by selecting an n=3 spectrum and a q95 = 3.6). However, RMPs lead to a changes in the density profile, not only in the pedestal area, but also deeper in the plasma core, limiting plasma performance. As a first contribution in this thesis we carefully investigate density pump-out, and show that it is the result of a change in particle transport (as opposed to a change in neutral fueling). A second contribution of this work is the introduction of a weighted magnetic diffusion coefficient (D/OFL) that allows us to make quantitative comparisons between experimental datasets from different Tokamak devices. By comparing D/OFL for MAST L-modes and DIII-D H-modes, we find that both machines exhibit a very different density pump-out for similar D/OFL values. Since turbulent particle transport is very different for L and H-modes, we investigate, as a third contribution of this work, the influence of RMPs on turbulent particle transport in both MAST and DIII-D. We find that while an increase in turbulent transport on MAST correlates well with density pump-out, no meaningful correlation was found for pedestal density changes in DIII-D. Therefore, as a final contribution in this thesis, we investigate how convective particle transport parallel to the magnetic field alters the density profiles. We compare the increase in convective parallel particle transport and find good agreement with experimental density profiles.

Issues in Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics: 2013 Edition

Issues in Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics: 2013 Edition
Author:
Publisher: ScholarlyEditions
Total Pages: 1198
Release: 2013-05-01
Genre: Science
ISBN: 1490107819

Issues in Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics: 2013 Edition is a ScholarlyEditions™ book that delivers timely, authoritative, and comprehensive information about High Energy Physics. The editors have built Issues in Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics: 2013 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about High Energy Physics in this book to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Nuclear, High Energy, Plasma, Particle, and Condensed Matter Physics: 2013 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

RMP Enhanced Transport and Rotation Screening in DIII-D Simulations

RMP Enhanced Transport and Rotation Screening in DIII-D Simulations
Author:
Publisher:
Total Pages: 9
Release: 2008
Genre:
ISBN:

The application of resonant magnetic perturbations (RMP) to DIII-D plasmas at low collisionality has achieved ELM suppression, primarily due to a pedestal density reduction. The mechanism of the enhanced particle transport is investigated in 3D MHD simulations with the NIMROD code. The simulations apply realistic vacuum fields from the DIII-D I-coils, C-coils and measure intrinsic error fields to an EFIT reconstructed DIII-D equilibrium, and allow the plasma to respond to the applied fields while the fields are fixed at the boundary, which lies in the vacuum region. A non-rotating plasma amplifies the resonant components of the applied fields by factors of 2-5. The poloidal velocity forms E x B convection cells crossing the separatrix, which push particles into the vacuum region and reduce the pedestal density. Low toroidal rotation at the separatrix reduces the resonant field amplitudes, but does not strongly affect the particle pumpout. At higher separatrix rotation, the poloidal E x B velocity is reduced by half, while the enhanced particle transport is entirely eliminated. A high collisionality DIII-D equilibrium with an experimentally measured rotation profile serves as the starting point for a simulation with odd parity I-coil fields that can ultimately be compared with experimental results. All of the NIMROD results are compared with analytic error field theory.

Resonant Particle Energy Transfer to Magnetic Perturbations with Application to the Geomagnetic Tail

Resonant Particle Energy Transfer to Magnetic Perturbations with Application to the Geomagnetic Tail
Author: F. C. Hoh
Publisher:
Total Pages: 9
Release: 1966
Genre:
ISBN:

It is shown how resonant particles can give up their kinetic energy to induced electric fields and hence cause amplification of the perturbed magnetic field energy. This is a simple physical picture of the instability of the sheet pinch. It reveals the nature of the instability and gives some insight into its degree of violence. (Author).

Magnetic Stochasticity in Magnetically Confined Fusion Plasmas

Magnetic Stochasticity in Magnetically Confined Fusion Plasmas
Author: Sadrilla Abdullaev
Publisher: Springer Science & Business Media
Total Pages: 422
Release: 2013-11-19
Genre: Science
ISBN: 3319018906

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.

Issues in Water and Power Engineering: 2011 Edition

Issues in Water and Power Engineering: 2011 Edition
Author:
Publisher: ScholarlyEditions
Total Pages: 651
Release: 2012-01-09
Genre: Technology & Engineering
ISBN: 1464965811

Issues in Water and Power Engineering / 2011 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Water and Power Engineering. The editors have built Issues in Water and Power Engineering: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Water and Power Engineering in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Water and Power Engineering: 2011 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Turbulent Transport in Magnetized Plasmas

Turbulent Transport in Magnetized Plasmas
Author: Wendell Horton
Publisher: World Scientific
Total Pages: 518
Release: 2012
Genre: Science
ISBN: 9814383546

The book explains how magnetized plasmas self-organize in states of electromagnetic turbulence that transports particles and energy out of the core plasma faster than anticipated by the fusion scientists designing magnetic confinement systems in the 20th century. It describes theory, experiments and simulations in a unified and up-to-date presentation of the issues of achieving nuclear fusion power.

Edge Localized Mode Control in DIII-D Using Magnetic Perturbation-Induced Pedestal Transport Changes

Edge Localized Mode Control in DIII-D Using Magnetic Perturbation-Induced Pedestal Transport Changes
Author: R. Schneider
Publisher:
Total Pages: 11
Release: 2006
Genre:
ISBN:

Edge localized mode (ELM) control is a critical issue for ITER because the impulsive power loading from ELMs is predicted to limit the divertor lifetime to only a few hundred full-length pulses. Consequently, a technique that replaces the ELM-induced transport with more continuous transport while preserving the H-mode pedestal height and core performance would significantly improve the viability of ITER. One approach is to use edge resonant magnetic perturbations (RMPs) to enhance pedestal transport enough to reduce the pedestal pressure gradient {del}p{sub ped} below the stability limit for Type I ELMs. In DIII-D, n = 3 RMPs have been used to eliminate Type I ELMs when the edge safety factor is in the resonant window q95 {approx} 3.5 without degrading confinement in H-modes with ITER-relevant pedestal collisionalities v*{sub e} {approx} 0.2. The RMP reduces {del}p{sub ped} as expected, with {del}p{sub ped} controlled by the RMP amplitude. Linear peeling-ballooning (P-B) stability analysis indicates that the ELMs are suppressed by reducing {del}p{sub ped} below the P-B stability limit. The {del}p{sub ped} reduction results primarily from an increase in particle transport, not electron thermal transport. This result is inconsistent with estimates based on quasi-linear stochastic diffusion theory based on the vacuum field (no screening of the RMP). The particle transport increase is accompanied by changes in toroidal rotation, radial electric field, and density fluctuation level {tilde n} in the pedestal, suggesting increased fluctuation-driven particle transport.