Download or read book Experimental study of the zonal flow dynamics in the magnetised plasmas of the stellarator experiment TJ K written by Bernhard Schmid and published by Cuvillier Verlag. This book was released on 2019-03-28 with total page 194 pages. Available in PDF, EPUB and Kindle. Book excerpt: The confinement quality of plasmas in toroidal magnetic fields is mainly limited by the turbulent transport perpendicular to the magnetic field. Zonal flows play an important role in fusion research as they are thought to be connected to the formation of a transport barrier in the edge of the confined plasma. This work concentrates on the investigation of the Reynolds stress drive of zonal flows with its connection to the geometry of the confining magnetic field and the influence of the collisionality. The measurements for this work have been conducted at the stellarator experiment TJ-K in plasmas dimensionally similar to fusion edge plasmas. The low temperatures allow the use of Langmuir probes in the entire confinement region. With a poloidal probe array, consisting of 128 Langmuir probes with 32 probes on each of four neighbouring magnetic flux surfaces, density and potential fluctuations can be acquired with high spatial and temporal resolution on the complete poloidal circumference. Die Einschlussqualität von Plasmen in toroidalen Magnetfeldern wird maßgeblich durch den turbulenten Transport senkrecht zum Magnetfeld limitiert. Zonalströmungen sind dabei für die Fusionsforschung von großer Bedeutung, da vermutet wird, dass sie mit der Bildung von Transportbarrieren in Zusammenhang stehen. Diese Arbeit beschäftigt sich vorwiegend mit der Untersuchung des Antriebsmechanismus von Zonalströmungen, im Speziellen mit der Abhängigkeit von der Magnetfeldgeometrie und dem Einfluss der Kollisionalität. Dazu wurden Messungen am Stellarator-Experiment TJ-K durchgeführt, in Plasmen, die dimensional ähnlich zu Randplasmen von Fusionsexperimenten sind. Die relativ geringen Plasmatemperaturen erlauben den Einsatz von Langmuir-Sonden im gesamten Einschlussgebiet. Mit einem poloidalen Sonden Array, bestehend aus 128 Sonden mit je 32 Sonden auf vier benachbarten Flussflächen, können Dichte- und Potentialfluktuationen mit hoher räumlicher und zeitlicher Auflösung gleichzeitig über den gesamten poloidalen Umfang aufgenommen werden.
Download or read book Zonal Jets written by Boris Galperin and published by Cambridge University Press. This book was released on 2019-02-28 with total page 527 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Investigation Into the Influence of Magnetic Field Structure on the Dynamical and Spatial Properties of Plasma Edge Turbulence in the Stellarator TJ K written by Stephen Garland and published by . This book was released on 2019 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A New Model for Plasma Confinement Times in Stellarators written by J. G. Gorman and published by . This book was released on 1968 with total page 32 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book On the Interactions of Magnetic Fluctuations Zonal Flows Microturbulence in Fusion Plasmas written by Zachary R. Williams and published by . This book was released on 2019 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: A key aspect of turbulent dynamics is the inherent coupling of fluctuations at disparate spatial scales. One significant multi-scale phenomenon is the degradation of zonal flows by large-scale radial magnetic perturbations that result in an increase of small-scale microturbulence and affiliated transport. Two prominent sources of radial magnetic field fluctuations are examined in this thesis, resonant magnetic perturbations (RMPs) in tokamaks and tearing modes in reversed-field pinches (RFPs). This interplay is studied with gyrokinetics to model DIII-D tokamak and MST RFP plasmas. An imposed magnetic perturbation that mimics a tearing mode increases the level of trapped-electron-mode turbulence to a level consistent with fluctuation and transport measurements in MST plasmas. This motivated a dedicated experiment on DIII-D to study the impact of varying RMP amplitude on turbulence in inboard-limited L-mode plasmas. Highlights of the theory-experiment comparison are presented. To study the self-consistent multi-scale interaction of the tearing mode physics, nonlinear simulations containing both tearing mode (driven from equilibrium current gradients) and microinstability scales are performed in a slab geometry. The system is characterized by distinct microinstability- and tearing-dominated regimes. Within the microturbulence-dominated phase, the slow tearing mode growth corresponds directly to a decay in zonal flow. The turbulence levels driven at both large and small scales is increased from single-scale simulations, clearly demonstrated the importance of cross scale interactions.
Download or read book Multi scale Investigation of Sheared Flows in Magnetized Plasmas written by and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Flows parallel and perpendicular to magnetic fields in a plasma are important phenomena in many areas of plasma science research. The presence of these spatially inhomogeneous flows is often associated with the stability of the plasma. In fusion plasmas, these sheared flows can be stabilizing while in space plasmas, these sheared flows can be destabilizing. Because of this, there is broad interest in understanding the coupling between plasma stability and plasma flows. This research project has engaged in a study of the plasma response to spatially inhomogeneous plasma flows using three different experimental devices: the Auburn Linear Experiment for Instability Studies (ALEXIS) and the Compact Toroidal Hybrid (CTH) stellarator devices at Auburn University, and the Space Plasma Simulation Chamber (SPSC) at the Naval Research Laboratory. This work has shown that there is a commonality of the plasma response to sheared flows across a wide range of plasma parameters and magnetic field geometries. The goal of this multi-device, multi-scale project is to understand how sheared flows established by the same underlying physical mechanisms lead to different plasma responses in fusion, laboratory, and space plasmas.
Download or read book Nuclear Fusion written by and published by . This book was released on 2001-11 with total page 636 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Investigation of the Interplay Between Flows Electronic Fields and Turbulence in Fusion Plasmas written by Juan Arturo Alonso de Pablo 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 The Beta Equilibrium Stability and Transport Codes written by Frances Bauer and published by Elsevier. This book was released on 2012-12-02 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Beta Equilibrium, Stability, and Transport Codes: Application to the Design of Stellarators covers the application of the BETA computer codes to the Heliotron E plasma confinement experiment. This book is the outgrowth of a collaboration between the Courant Institute at New York University and the Plasma Physics Laboratory at Kyoto University. After briefly dealing with the history of the codes and the design of new stellarator experiments, this five-chapter book goes on presenting 15 typical runs of the BETA equilibrium, stability, and transport codes. Included with each run is a statement relating the physics of the example to the computational model. The following chapters focus on the revisions of the BETA equilibrium code by implementing a simplified neoclassical transport theory defining the geometric confinement time output by the equilibrium code. The concluding chapter provides a FORTRAN listing of the transport code.
Download or read book Turbulence and Instabilities in Magnetised Plasmas written by Bruce D. Scott and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Ever since the first observations of turbulent fluctuations in laboratory plasma experiments in the years around 1980, turbulence in magnetised plasmas has been a subject of vigorous interest in the field of plasma physics and magnetic confinement. The first of a two-volume set, this book begins with an overview of the essential nature of a plasma and a magnetised plasma, then turbulence and plasma turbulence are introduced conceptually and mathematically. There follows a theoretical interlude developing the concepts of fluid and plasma dynamics. After this, concepts of energetic consistency and nonlinear instability and mode structure are emphasised. The effects of magnetic shear and curvature, and open and closed magnetic field line flux surfaces, and finally the interaction with both background and self-generated flows, are covered. An interlude points to a second volume treating temperature gradients and fluctuations, gyrokinetic and gyrofluid theory, and the interplay with magnetohydrodynamic instabilities. Part of IOP Series in Plasma Physics.
Download or read book An Experimental Study of Continuous Plasma Flows Driven by a Confined Arc in a Transverse Magnetic Field written by R. L. Barger and published by . This book was released on 1961 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Interaction of Ambipolar Plasma Flow with Magnetic Islands in a Quasi axisymmetric Stellarator written by L. Owen and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A reference equilibrium for the U.S. National Compact Stellarator Experiment is predicted to be sufficiently close to quasi-symmetry to allow the plasma to flow in the toroidal direction with little viscous damping, yet to have sufficiently large deviations from quasi-symmetry that nonambipolarity significantly affects the physics of the shielding of resonant magnetic perturbations by plasma flow. The unperturbed velocity profile is modified by the presence of an ambipolar potential, which broadens the profile and improves the shielding near the plasma edge. In the presence of a resonant magnetic field perturbation, nonambipolar transport produces a radial current, and the resulting jxB force resists departures from the ambipolar velocity and enhances the shielding.
Download or read book Interaction Dynamics of High Reynolds Number Magnetized Plasma Flow on the CTIX Plasma Accelerator written by Stephen James Howard and published by . This book was released on 2006 with total page 556 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Zonal Flow Dynamics and Size scaling of Anomalous Transport written by Liu Chen and published by . This book was released on 2003 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Investigation of Magnetic Field and Current Topology in Z pinch Plasmas written by Derek Alexander Mariscal and published by . This book was released on 2015 with total page 233 pages. Available in PDF, EPUB and Kindle. Book excerpt: Z-pinch plasma dynamics are largely determined by the current and magnetic field topology of the system. Measurement of the magnetic fields allows for the inference of the current distribution, but is in practice difficult to measure in experiments. This leads to a high dependence on numerical simulations for extracting this information, but without quality experimental data, may not be entirely reliable for this purpose. Proton deflectometry, or proton radiography, is a relatively new diagnostic developed for investigating electromagnetic fields in high energy-density plasmas since it provides data with high spatial and temporal resolution compared to traditional field diagnostics. It was developed in the laser-plasma-interaction community as a means of determining electric and magnetic field strength and orientation during laser-driven plasma experiments. In this work, the method was developed for use on Mega-Amp-scale pulsed-power-driven plasma experiments. In one configuration, a proton beam was directed radially, with respect to the z-axis of a pulsed-power-driven short-circuit load. In this setup, an azimuthally symmetric magnetic field is generated around the short-circuit load, as a current pulse, 0.6 MA in 0-100% rise-time 200 ns with an approximately sine-squared waveform. Scaled laboratory astrophysics experiments modeling the dynamics of universal astrophysical phenomena such as plasma jets have recently become an area of great interest. Such experiments are vital to resolving long-standing questions about the roles of various physical processes in the dynamics of such objects. The application of proton deflectometry to scaled laboratory astrophysics experiments revealed details of the current and magnetic field topology which was previously accessible only in numerical codes. One such load is the radial foil load, designed to replicate the propagation of a jet during the formation stages of a star. The data from this work was used to benchmark a resistive MHD code, Gorgon, designed to reproduce the Z-pinch experiments as well as astrophysical phenomena. The simulation results were found to agree with the experimental data, meaning that the current and magnetic field topology could be recovered from the code. The demonstration of this diagnostic technique opens up many possibilities for examining the current and magnetic field topology in other Z-pinch experiments.
Download or read book Constructing Integrable High pressure Full current Free boundary Stellarator Magnetohydrodynamic Equilibrium Solutions written by S. R. Hudson and published by . This book was released on 2003 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics Basis for High Beta Low Aspect Ratio Stellarator Experiments written by G. H. Neilson and published by . This book was released on 1999 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt:
