Download or read book Extended Magnetohydrodynamic Modeling of Plasma Relaxation Dynamics in the Reversed field Pinch written by and published by . This book was released on 2015 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nonlinear plasma relaxation dynamics in reversed-field pinch (RFP) conditions are investigated using extended magnetohydrodynamic modeling with the NIMROD code [Sovinec et. al. JCP 195 (2004)]. The computations display quasi-periodic relaxation events, consistent with the RFP sawtooth cycle. The first event occurs from a saturated single-helicity state and is not representative of the multi-helicity conditions in typical RFP discharges. The MHD and Hall dynamo electric fields cooperate during the initial relaxation, and the change in the plasma flow parallel to the magnetic field is in the direction of the Lorentz force density and opposite to the change in parallel current density. In subsequent events, the MHD dynamo relaxes the parallel current and is opposed by the Hall dynamo, which is smaller in magnitude. The associated Lorentz force density drives changes in flow that are in the same direction as the change in current, in agreement with experimental observations [Kuritsyn et. al. POP 055903 (2009)]. Changes in total momentum are due to viscous coupling to the wall; radial transport occurs through Maxwell stresses associated with current relaxation. The magnetic and hybrid helicity are well conserved relative to magnetic energy over the relaxation events. The helicities change by

Download or read book Magnetohydrodynamics of Plasma Relaxation written by S. Ortolani and published by World Scientific. This book was released on 1993 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book gives a concise description of the phenomenon of plasma relaxation from the point of view of resistive magnetohydrodynamic (MHD) theory. Magnetized plasmas relax when they seek their natural state of lowest energy subject to certain topological constraints imposed by the magnetic field. Relaxation may be fast and dynamic or slow and gradual depending on the external environment in which the magnetoplasma system evolves. Relaxation occurs throughout the universe and may describe such diverse phenomena as dynamos, solar flares, and the operation of magnetic fusion energy experiments. This book concentrates on the dynamic, rather than variational aspects of relaxation. While the processes described are general, the book focuses on the reversed-field pinch experiment as a paradigm for plasma relaxation and dynamo action. Examples from other branches of plasma physics are also discussed. The authors draw upon their extensive experience in numerical and experimental studies of relaxation.

Download or read book Relaxation Model for Extended Magnetohydrodynamics written by and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: It is shown that the two-fluid model under a generalized Ohm's law formulation and the resistive magnetohydrodynamics (MHD) can both be described as relaxation systems. In the relaxation model, the under-resolved stiff source terms constrain the dynamics of a set of hyperbolic equations to give the correct asymptotic solution. When applied to the collisional two-fluid model, the relaxation of fast time scales associated with displacement current and finite electron mass allows for a natural transition from a system where Ohm's law determines the current density to a system where Ohm's law determines the electric field. This result is used to derive novel algorithms, which allow for multiscale simulation of low and high frequency extended-MHD physics. This relaxation formulation offers an efficient way to implicitly advance the Hall term and naturally simulate a plasma-vacuum interface without invoking phenomenological models. The relaxation model is implemented as an extended-MHD code, which is used to analyze pulsed power loads such as wire arrays and ablating foils. Two-dimensional simulations of pulsed power loads are compared for extended-MHD and MHD. For these simulations, it is also shown that the relaxation model properly recovers the resistive-MHD limit.

Download or read book Ideal Magnetohydrodynamics written by Jeffrey P. Freidberg and published by Plenum Publishing Corporation. This book was released on 1987 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Lundquist Number Scaling in Mst Reversed field Pinch Plasmas written by Stephanie Zofia Kubala and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nonlinear MHD fluctuations appear in both natural and magnetic confinement settings, such as the solar wind, self-organization dynamics in the RFP and spheromak, and current disruptions in tokamak plasmas. In this thesis, parameter scaling experiments oriented toward nonlinear MHD dynamics in RFP plasmas are presented. Experimental data have been gathered spanning a wide range of parameter space characterized by Lundquist number, $S \sim 10^4$ - $10^7$, and density, $n_e/n_G$, where $n_G$ is the empirical density limit. A new programmable power supply allows low-current, low-S operation, which overlaps with parameters available in numerical modeling. Experimental S scalings of magnetic fluctuation amplitude agree well with those from the nonlinear MHD codes DEBS and NIMROD. A transition from quasi-continuous activity to bursty relaxation having discrete sawtooth events is observed in going from low to high $S$, with a threshold at around $S \sim 10^5$. The spectral properties of the magnetic fluctuations change at this transition, including a reduction in fluctuation phase velocity that suggests plasma flow and/or flow profile changes. Momentum transport and flattening of the flow profile are known features associated with sawtooth relaxation in RFP plasmas.

Download or read book The Effects of Magnetic Field Errors on Reversed Field Pinch Plasma written by Abdulgader Feturi Almagri and published by . This book was released on 1990 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physics of Reversed field Pinch Profile Sustainment written by and published by . This book was released on 1984 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A description of the Reversed-Field Pinch (RFP) is given, emphasizing the necessity of a magnetohydrodynamic (MHD) or kinetic process to sustain field reversal. Three sustainment mechanisms are reviewed: the MHD dynamo, the tangled discharge model, and nonlocal resistivity. A slab model of steady (ohmic) states is described. A relationship between ohmic state wave numbers and the minimum amplitude of nonsymmetric field components is given. If ohmic states are the sole source of the sustainment process, their wave lengths are probably much longer than the minor diameter of the plasma. Otherwise field asymmetries would exceed those observed in experiments. It is noted that internal field data are still limited, restricting the generality of our comments.

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 994 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Lectures in Magnetohydrodynamics written by Dalton D. Schnack and published by Springer. This book was released on 2009-08-29 with total page 323 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetohydrodynamics, or MHD, is a theoretical way of describing the statics and dynamics of electrically conducting uids. The most important of these uids occurring in both nature and the laboratory are ionized gases, called plasmas. These have the simultaneous properties of conducting electricity and being electrically charge neutral on almost all length scales. The study of these gases is called plasma physics. MHD is the poor cousin of plasma physics. It is the simplest theory of plasma dynamics. In most introductory courses, it is usually afforded a short chapter or lecture at most: Alfven ́ waves, the kink mode, and that is it. (Now, on to Landau damping!) In advanced plasma courses, such as those dealing with waves or kinetic theory, it is given an even more cursory treatment, a brief mention on the way to things more profound and interesting. (It is just MHD! Besides, real plasma phy- cists do kinetic theory!) Nonetheless, MHD is an indispensable tool in all applications of plasma physics.

Download or read book Poloidal Rotation of Reversed Field Pinch Plasma written by H. Arimoto and published by . This book was released on 1985 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book A New Approach to Magnetohydrodynamic Stability written by P. H. Sakanaka and published by . This book was released on 1973 with total page 64 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Reversed Field Pinch Magnetic Equilibrium and Profile Dynamics in Extrap T1 upgrade written by Peter Nordlund and published by . This book was released on 1992 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fusion Energy Update written by and published by . This book was released on 1986 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Physics Briefs written by and published by . This book was released on 1991 with total page 1132 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Energy Research Abstracts written by and published by . This book was released on 1993-10 with total page 578 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Plasma Physics Proceedings Of The 10th European School written by N L Tsintsadze and published by #N/A. This book was released on 1991-08-12 with total page 581 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Development of an Extended Magnetohydrodynamic Model for Anisotropic Plasmas microform written by Ken Miura and published by Library and Archives Canada = Bibliothèque et Archives Canada. This book was released on 2004 with total page 186 pages. Available in PDF, EPUB and Kindle. Book excerpt: An extended magnetohydrodynamic (MHD) model capable of modelling anisotropic and non-equilibrium plasma flows is proposed based on a ten-moment approximation to the solution of the Boltzmann equations, having a full second-order pressure tensor. The extended MHD model has been derived using many of the assumptions and methods used to derive the standard MHD equations. The model makes use of separate pressure and energy equations for the ions and electrons and a Bhatnagar-Gross-Krook (BGK) collision operator is used to model ion and electron collisional processes. Eigenstructure analysis is used to explore the mathematical and physical characteristics as well as the hyperbolicity and realizability regimes of the model. A point-implicit finite-volume upwind scheme with second-order time stepping and a limited second-order spatial discretization procedure is used to examine the capabilities of the model and compare its predictions to those provided by the ideal MHD description for several one-dimensional plasma flow problems including a classic shock tube problem, the Brio-Wu MHD test case, and a modified Brio-Wu test case. The numerical results and limitations of the model are discussed along with future directions for this line of research.