Download or read book Microwave Imaging Diagnostics for Imaging and Visualization of Magnetohydrodynamic Instabilities in Magnetic Fusion Plasmas written by Ming Chen and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Microwave imaging diagnostics in magnetic fusion plasmas consist of both active and passive imaging. Microwave Imaging Reflectometry (MIR) is an active radar-like techniques in which plasma is illuminated with a broad range of microwave frequencies, the electron density and its fluctuation information at cutoff layers are carried by the reflected beams and imaged onto an array of detectors. Electron Cyclotron Emission imaging (ECEI) is a passive radiometric diagnostic system, collecting the radiation emitted by electron gyrating along magnetic field lines so as to provide visualization of the local electron temperature and its fluctuation. To properly interpret the measured signals from these diagnostics and make comparison with theoretical simulations which can advance our understanding towards plasma physics, forward modelling is of significant importance. For the purpose of performing the forward modelling, synthetic diagnostics are being developed, which are aimed at simulating the response of diagnostic systems under actual experimental scenarios and are the key to optimizing system design and drawing quantitative inferences from experimental data. This dissertation focuses on the development and application of synthetic diagnostic for the microwave imaging diagnostic systems. The Edge Harmonic Oscillation (EHO) mode is one of the characteristic modes during the Quiescent High confinement phase in tokamaks that provide an edge transport channel in a moderate manner. Recent theoretical work and extensive experimental observations have suggested that the large rotational E×B shear is the key to destabilize, and thus prevent, the EHO from entering the explosive phase as an Edge Localized Mode (ELM). However, detailed mechanisms concerning this process still remain vague. We employed a synthetic MIR diagnostic to compare the experimental MIR measurement with the linear MHD modeling of the Edge Harmonic Oscillations to draw quantitative interpretation of MIR exclusive observation. The work found that the E×B shear introduced a sheared structure on EHOs in a narrow range near the pedestal top. Furthermore, we performed continuous tracking on how the E×B shear affects the EHO mode structure in order to search for a possible explanation of the EHO’s saturation mechanism under ELM instability. Together with MIR, another edge density fluctuation diagnostic –Beam Emission Spectroscopy is employed to observe the eigenmode structure evolution of EHO in the pedestal region in the radial and poloidal directions, respectively. Our results show that the EHO mode’s radial wavenumber is strongly correlated with the E×B shear rate, while the poloidal wavenumber is less affected by the E×B shear rate. Since the shear is mainly in the poloidal direction, the larger E×B shear tends to elongate the mode more in the poloidal direction which in turn affects the radial wavenumber more. It is also observed that only the density scale length is correlated with the E×B shear rate, implying that the EHOs only modulate the particle transport rather than thermal transport. This modulation could contribute to maintaining the QH-mode under the ELM instability with good thermal confinement. The synthetic ECEI diagnostic has been recently developed and benchmark tested. The synthetic ECEI diagnostic is applied to evaluate the improvement arising from the application of Field Curvature Adjustment (FCA) lenses in the design of the upgraded EAST tokamak ECEI system. The synthetic ECEI diagnostic results show that, with FCA lenses applied, the upgraded ECEI system has significant advantages to focus on high poloidal wavenumber structures with the aberrations from the spherical surfaces corrected and the various artifacts related to the field curvature suppressed.
Download or read book Microwave Diagnostics for Magnetic Fusion Devices written by Liubing Yu and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: To tackle the energy shortage problems that we are facing, many scientists are trying to achieve controlled fusion to provide clean and sustainable energy. Many large Tokamaks, which is the most promising device concept, have been built worldwide and three of them (DIII-D, NSTX, C-Mod) are currently in operation in the U.S. To understand the details of magnetic fusion plasma physics, a variety of microwave diagnostics are applied to measure the plasma properties from the millions of degrees plasma in a nonperturbative fashion. Our research group, the Plasma Diagnostics Group, under the Davis MM-Wave Research Center (DMRC), focuses on developing advanced microwave diagnostic tools. The Electron Cyclotron Emission Imaging (ECEI) diagnostic, a passive radiometric microwave diagnostic, is an extremely useful imaging tool invented in this group to study electron temperature and its fluctuations. The Microwave Imaging Reflectometry (MIR) technique is also another imaging tool pioneered in this group, and its purpose is to study electron density fluctuations using an imaging radar approach. Finally, the Far Infrared Tangential Interferometry/ Polarimetry (FIReTIP) system is a density and magnetic field diagnostic tool. This dissertation introduces the principles, structure, recent technology advances, and some physical studies concerning these three systems. The combined ECEI and MIR systems on the DIII-D (located at General Atomics in San Diego) provide simultaneous electron temperature and density fluctuation imaging at the same plasma volume. The ECEI system consists of two major parts: the optical and array system, which images and downconverts the millimeter wave ECE radiation, and the electronics, which detects the radiation power in each designed band. This dissertation concerns two recent upgrades made by our group: one is the use of the zero bias Schottky detectors in the IF electronics which has greatly decreased the noise level, and the other is the expanded radial coverage which doubles the radial view in the plasma. For the MIR system, the synthetic diagnostic modeling has guided the very successful optic and array design; some details concerning the transmitter, receiver, and electronics are presented. In this dissertation, several methods for the ECEI/MIR time calibration were conceived, applied, and compared; in addition, the ECEI and MIR systems are also time calibrated with respect to two other important diagnostics, the ECE radiometer and magnetic fluctuation diagnostic systems.Intense bursts of mm-wave emission with durations of 5-10 [mu]s have been observed on DIII-D by both ECE radiometer and ECEI systems during edge localized modes, Quiet H-mode (QH) modes, and the precursor before disruptions. Both the ECE radiometer system and the ECEI system employ heterodyne detection methods and have overlapping intermediate frequency (IF) bands. A new RF spectrometer, spanning this IF frequency range of approximately 2-10 GHz, has been installed on the DIII-D tokamak in order to more fully characterize the frequency, intensity, and localization of these bursts. Herein, the data for the H mode case and QH-mode case will be discussed and scrutinized in order to constrain the needed model to explain the bursts. As a trial model, the Cyclotron AutoResonance Maser (CARM) and Gyro-BWO models are proposed to explain these bursts, which require further theory, experimental, and simulation support. The multichannel FIReTIP system provides line-integrated plasma density and magnetic information from multiple viewing chords on the midplane of the NSTX device. Extremely wide bandwidth phase comparator electronics for the FIReTIP system were developed and installed on the NSTX device in 2009. This allows the system video bandwidth, previously limited to ~250 kHz, to extend out to ~500 kHz when operated as a simultaneous interferometer/polarimeter system and as high as 4 MHz when operated in an interferometry-only configuration. The new electronics provides simultaneous interferometer phase measurement data using two distinct phase comparator methods. The first is a digital fringe counter (FC) approach limited to a video bandwidth of ~500 kHz, while the second is an analog demodulator or in-phase and quadrature (IQ) approach that achieves the full 4 MHz video bandwidth. New algorithms have been developed to process the FIReTIP data for both regular (post-shot) and real-time density calculations, with reliability checks conducted using laser Thompson Scattering data where available.
Download or read book Recent Advancements in Microwave Imaging Plasma Diagnostics written by Hyeon Keo Park and published by . This book was released on 2002 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Microwave Imaging Diagnostics for Plasma Fluctuation Studies written by Jian Wang and published by . This book was released on 2005 with total page 396 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 1992 with total page 820 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 1981 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 652 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1999 with total page 974 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Assessment of the Department of Energy s Office of Fusion Energy Sciences Program written by National Research Council and published by National Academies Press. This book was released on 2001-06-07 with total page 112 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this assessment of the fusion energy sciences program of the Department of Energy's (DOE's) Office of Science is to evaluate the quality of the research program and to provide guidance for the future program strategy aimed at strengthening the research component of the program. The committee focused its review of the fusion program on magnetic confinement, or magnetic fusion energy (MFE), and touched only briefly on inertial fusion energy (IFE), because MFE-relevant research accounts for roughly 95 percent of the funding in the Office of Science's fusion program. Unless otherwise noted, all references to fusion in this report should be assumed to refer to magnetic fusion. Fusion research carried out in the United States under the sponsorship of the Office of Fusion Energy Sciences (OFES) has made remarkable strides over the years and recently passed several important milestones. For example, weakly burning plasmas with temperatures greatly exceeding those on the surface of the Sun have been created and diagnosed. Significant progress has been made in understanding and controlling instabilities and turbulence in plasma fusion experiments, thereby facilitating improved plasma confinement-remotely controlling turbulence in a 100-million-degree medium is a premier scientific achievement by any measure. Theory and modeling are now able to provide useful insights into instabilities and to guide experiments. Experiments and associated diagnostics are now able to extract enough information about the processes occurring in high-temperature plasmas to guide further developments in theory and modeling. Many of the major experimental and theoretical tools that have been developed are now converging to produce a qualitative change in the program's approach to scientific discovery. The U.S. program has traditionally been an important source of innovation and discovery for the international fusion energy effort. The goal of understanding at a fundamental level the physical processes governing observed plasma behavior has been a distinguishing feature of the program.
Download or read book Plasma Physics written by Alexander Piel and published by Springer. This book was released on 2017-09-07 with total page 473 pages. Available in PDF, EPUB and Kindle. Book excerpt: The enlarged new edition of this textbook provides a comprehensive introduction to the basic processes in plasmas and demonstrates that the same fundamental concepts describe cold gas-discharge plasmas, space plasmas, and hot fusion plasmas. Starting from particle drifts in magnetic fields, the principles of magnetic confinement fusion are explained and compared with laser fusion. Collective processes are discussed in terms of plasma waves and instabilities. The concepts of plasma description by magnetohydrodynamics, kinetic theory, and particle simulation are stepwise introduced. Space charge effects in sheath regions, double layers and plasma diodes are given the necessary attention. The novel fundamental mechanisms of dusty plasmas are explored and integrated into the framework of conventional plasmas. The book concludes with a concise description of modern plasma discharges. Written by an internationally renowned researcher in experimental plasma physics, the text keeps the mathematical apparatus simple and emphasizes the underlying concepts. The guidelines of plasma physics are illustrated by a host of practical examples, preferentially from plasma diagnostics. There, Langmuir probe methods, laser interferometry, ionospheric sounding, Faraday rotation, and diagnostics of dusty plasmas are discussed. Though primarily addressing students in plasma physics, the book is easily accessible for researchers in neighboring disciplines, such as space science, astrophysics, material science, applied physics, and electrical engineering. This second edition has been thoroughly revised and contains substantially enlarged chapters on plasma diagnostics, dusty plasmas and plasma discharges. Probe techniques have been rearranged into basic theory and a host of practical examples for probe techniques in dc, rf, and space plasmas. New topics in dusty plasmas, such as plasma crystals, Yukawa balls, phase transitions and attractive forces have been adopted. The chapter on plasma discharges now contains a new section on conventional and high-power impulse magnetron sputtering. The recently discovered electrical asymmetry effect in capacitive rf-discharges is described. The text is based on an introductory course to plasma physics and advanced courses in plasma diagnostics, dusty plasmas, and plasma waves, which the author has taught at Kiel University for three decades. The pedagogical approach combines detailed explanations, a large number of illustrative figures, short summaries of the basics at the end of each chapter, and a selection of problems with detailed solutions.
Download or read book Plasma Science written by National Academies of Sciences Engineering and Medicine and published by . This book was released on 2021-02-28 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasma Science and Engineering transforms fundamental scientific research into powerful societal applications, from materials processing and healthcare to forecasting space weather. Plasma Science: Enabling Technology, Sustainability, Security and Exploration discusses the importance of plasma research, identifies important grand challenges for the next decade, and makes recommendations on funding and workforce. This publication will help federal agencies, policymakers, and academic leadership understand the importance of plasma research and make informed decisions about plasma science funding, workforce, and research directions.
Download or read book Frontiers in High Energy Density Physics written by National Research Council and published by National Academies Press. This book was released on 2003-05-11 with total page 177 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent scientific and technical advances have made it possible to create matter in the laboratory under conditions relevant to astrophysical systems such as supernovae and black holes. These advances will also benefit inertial confinement fusion research and the nation's nuclear weapon's program. The report describes the major research facilities on which such high energy density conditions can be achieved and lists a number of key scientific questions about high energy density physics that can be addressed by this research. Several recommendations are presented that would facilitate the development of a comprehensive strategy for realizing these research opportunities.
Download or read book Principles of Stellar Dynamics written by S. Chandrasekhar and published by Courier Corporation. This book was released on 2005-05-13 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this classic text, a Nobel Prize-winning astrophysicist presents the theory of stellar dynamics as a branch of classical dynamics--a discipline in the same general category as celestial mechanics. His method offers the advantages of clarifying the theory's fundamental issues and defining its underlying motivations. S. Chandrasekhar investigates two areas. The first concerns problems in which the time of relaxation of a stellar system is central. His method consists of analyzing the effects of stellar encounters in terms of the two-body problem of classical dynamics and applying this theory to the dynamics of star clusters. The second area investigates problems centering around Liouville's theorem and the solutions of the equation of continuity; here, the author discusses the dynamic implications of the existence of a field of differential motions, which appears to be the most striking kinematic feature of the galaxy and the extragalactic systems. This edition includes two papers by the author that were published after Principles of Stellar Dynamics and that have been studied and quoted extensively: "New Methods in Stellar Dynamics" (originally published in the Annals of the New York Academy of Sciences) and "Dynamical Friction" (originally published in The Astrophysical Journal).
Download or read book Nuclear Fusion written by and published by . This book was released on 2001-05 with total page 686 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Principles of Plasma Diagnostics written by I. H. Hutchinson and published by Cambridge University Press. This book was released on 2005-07-14 with total page 460 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a systematic introduction to the physics of plasma diagnostics measurements. It develops from first principles the concepts needed to plan, execute and interpret plasma measurements, making it a suitable book for graduate students and professionals with little plasma physics background. The book will also be a valuable reference for seasoned plasma physicists, both experimental and theoretical, as well as those with an interest in space and astrophysical applications. This second edition is thoroughly revised and updated, with new sections and chapters covering recent developments in the field.
Download or read book Electromagnetic Waves For Thermonuclear Fusion Research written by Ernesto Mazzucato and published by World Scientific. This book was released on 2014-04-02 with total page 223 pages. Available in PDF, EPUB and Kindle. Book excerpt: The science of magnetically confined plasmas covers the entire spectrum of physics from classical and relativistic electrodynamics to quantum mechanics. During the last sixty years of research, our initial primitive understanding of plasma physics has made impressive progress thanks to a variety of experiments — from tabletop devices with plasma temperatures of a few thousands of degrees and confinement times of less than 100 microseconds, to large tokamaks with plasma temperatures of up to five hundred million degrees and confinement times approaching one second. We discovered that plasma confinement is impaired by a variety of instabilities leading to turbulent processes with scales ranging from the plasma size to a few millimeters. Understanding these phenomena, which have slowed down progress towards a fusion reactor, requires the use of very sophisticated diagnostic tools, many of which employ electromagnetic waves.The primary objective of this book is to discuss the fundamental physics upon which the application of electromagnetic waves to the study of magnetically confined plasmas is based.
Download or read book Nuclear Science Information of Japan Oral Presentation written by and published by . This book was released on 1993 with total page 568 pages. Available in PDF, EPUB and Kindle. Book excerpt:
