Feasibility Study of an Iterative Finite Difference Approach to Kinetic Modeling of Neutral Particles in Edge Plasmas
Author: Mark Lloyd Adams
Publisher:
Published: 1997
Total Pages: 22
ISBN-13:
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Author: Mark Lloyd Adams
Publisher:
Published: 1997
Total Pages: 22
ISBN-13:
DOWNLOAD EBOOKAuthor: Ryan Joseph Norval
Publisher:
Published: 2019
Total Pages: 145
ISBN-13:
DOWNLOAD EBOOKReversed field pinch (RFP) plasmas are high density, moderate temperature plasmas, which efficiently utilize magnetic fields for fusion research and astrophysical studies. RFPs are operated with either a multihelicity (MH) or a quasi-single helicity (QSH) magnetic core. Core plasma confinement and heating is the main goal of RFP research. The influence of the plasma edge on the RFP energy balance has not been systematically studied. The Madison Symmetric Torus (MST), a large RFP device with a limiter, is ideal for studying the plasma-wall interaction (PWI) in the RFP edge. The RFP edge is a domain with a high fraction of neutral particles produced by neutralization of impinging plasma ions on the vessel wall and limiter. Neutral particles affect the plasma energy balance through the processes of dissociation, ionization, charge exchange, and radiation. In this work, boundary-viewing cameras are used to image the plasma edge. Absolute calibration of the camera system enables measurement of the D[subscript alpha] photon flux generated by PWI. Langmuir probes measure electron density (n[subscript e]) and electron temperature (T[subscript e]) in the edge. Core n[subscript e] and T[subscript e] are measured by an interferometer and a Thomson scattering diagnostic respectively. Knowledge of n[subscript e] and T[subscript e] is required to convert photon fluxes into particle fluxes by converting D[subscript alpha] atomic line emission intensities into particle fluxes using appropriate atomic data for excitation and radiative decay of the relevant line transitions. A helical bulge in the plasma pressure was discovered in QSH plasmas. The edge pressure maximum is phase-aligned to the magnetic mode in the plasma core domain. By referring to these experimental data from cameras and Langmuir probes, a three-dimensional (3D) plasma edge temperature and density was constructed and used to the fully model the 3D kinetic neutral particle model EIRENE. A method of comparison between modeled EIRENE images of D[subscript alpha] emission with experimental data served as a first detailed benchmark for MST. Synthetic images are compared to experimental images validating the EIRENE model. For the first time, 3D profiles of neutral density in MST are constructed using EIRENE. This fully 3D neutral distribution then enabled an investigation of the role of neutral particles to the RFP energy balance. Neutral particles account for a significant percentage of power loss in QSH plasmas. Neutral particles account for up to 30% of the power losses in the plasma edge domain of MST. The main fraction is established by electron-impact ionization and molecular dissociation events. The remaining fraction is dissipated by charge-exchange. By injecting gas directly into the helical bulge, a QSH plasma may be fueled at 74% efficiency compared to 52% fueling efficiency at other locations. The localization of the PWI in the QSH mode may be exploitable in future RFPs by designing divertor-like edges where particles can be effectively pumped out. In addition control of the PWI could reduce energy losses in QSH plasma by up to 20% of total input power. Understanding the magnitude of these losses and what drives them can lead to improved optimization of the RFP as a fusion device.
Author:
Publisher:
Published: 1667
Total Pages: 12
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DOWNLOAD EBOOKAuthor: J. Killeen
Publisher: Springer
Published: 1986-04
Total Pages: 216
ISBN-13:
DOWNLOAD EBOOKBecause magnetically confined plasmas are generally not found in a state of thermodynamic equilibrium, they have been studied extensively with methods of applied kinetic theory. In closed magnetic field line confinement devices such as the tokamak, non-Maxwellian distortions usually occur as a result of auxiliary heating and transport. In magnetic mirror configurations even the intended steady state plasma is far from local thermodynamic equilibrium because of losses along open magnetic field lines. In both of these major fusion devices, kinetic models based on the Boltzmann equation with Fokker-Planck collision terms have been successful in representing plasma behavior. The heating of plasmas by energetic neutral beams or microwaves, the production and thermalization of a-particles in thermonuclear reactor plasmas, the study of runaway electrons in tokamaks, and the performance of two-energy compo nent fusion reactors are some examples of processes in which the solution of kinetic equations is appropriate and, moreover, generally necessary for an understanding of the plasma dynamics. Ultimately, the problem is to solve a nonlinear partial differential equation for the distribution function of each charged plasma species in terms of six phase space variables and time. The dimensionality of the problem may be reduced through imposing certain symmetry conditions. For example, fewer spatial dimensions are needed if either the magnetic field is taken to be uniform or the magnetic field inhomogeneity enters principally through its variation along the direction of the field.
Author: Konstantin Matyash
Publisher:
Published: 2003
Total Pages: 192
ISBN-13:
DOWNLOAD EBOOKAuthor: Mark Edward Valenti
Publisher:
Published: 1992
Total Pages: 108
ISBN-13:
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Publisher:
Published: 1983-07
Total Pages: 616
ISBN-13:
DOWNLOAD EBOOKAuthor: Tetsu Mieno
Publisher: BoD – Books on Demand
Published: 2020-08-26
Total Pages: 228
ISBN-13: 1838804706
DOWNLOAD EBOOKIn the field of plasma physics, plasmas (including charged fine particles) have been actively studied for more than 40 years, and special features of wave phenomena, self-organizations of the particles, potential formations, fluid-like motions of the particles, generations of fine particles in the plasmas, etc. have been investigated. Here, these plasmas are called “fine particle plasmas”, which are also called “dusty plasmas” and “complex plasmas”. This book intends to provide the reader with the recent progress of studies of fine particle plasmas from the viewpoints of wide and interdisciplinary directions, such as self-organized fine particles, Coulomb crystal formation, behaviors of fine particles, their stability, and syntheses of nano-sized particles in reactive plasmas. Further, the phenomena of dense grain particles and the effects of massive neutrinos in galaxy clustering are included.
Author: R.J Goldston
Publisher: CRC Press
Published: 2020-07-14
Total Pages: 514
ISBN-13: 9781439822074
DOWNLOAD EBOOKIntroduction to Plasma Physics is the standard text for an introductory lecture course on plasma physics. The text’s six sections lead readers systematically and comprehensively through the fundamentals of modern plasma physics. Sections on single-particle motion, plasmas as fluids, and collisional processes in plasmas lay the groundwork for a thorough understanding of the subject. The authors take care to place the material in its historical context for a rich understanding of the ideas presented. They also emphasize the importance of medical imaging in radiotherapy, providing a logical link to more advanced works in the area. The text includes problems, tables, and illustrations as well as a thorough index and a complete list of references.