Download or read book Development and Applications of Synthetic Microwave Imaging Reflectometry MIR Diagnostics written by Xiaoxin Ren and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Tokamak is one of the most-researched candidates for producing controlled thermonuclear fusion power. Its confinement quality is highly limited by micro-scale as well as MHD turbulence in plasma. The UC Davis Millimeter-Wave group is dedicated to the development of tools, mainly Electron Cyclotron Emission Imaging (ECEI) and Microwave Imaging Reflectometry (MIR) to diagnose turbulence in plasmas. Here, ECEI and MIR are used to diagnose temperature and density fluctuations in the cross section of a Tokamak. In this dissertation, the focus is on the development of the MIR system, and more specifically, on the development and applications of a synthetic MIR diagnostic. The synthetic MIR helps in the design stage by optimizing and validating optical lens parameters of the imaging system. It also helps to determine the possible operating space of a MIR system. With the help of synthetic MIR, an MIR system was successfully installed on the DIII-D Tokamak. MIR then achieved great performance in measuring a wide range of MHD instabilities, for instance, strong inter-ELM modes in H-mode operation plasmas. Synthetic MIR then helps to interpret experimental data, and was used for edge harmonic oscillation studies and provides a proxy between the plasma simulation codes and real plasma. This dissertation first emphasizes the importance of fusion and fusion turbulence diagnostics; it then covers the principles of the MIR system, the hardware of the DIII-D MIR system, and then goes deeply into the process of synthetic MIR. Afterwards, the dissertation focuses on the analytical results from synthetic MIR simulations for defining the MIR instrumental function, and also how it helped to calibrate the DIII-D MIR system and interpret experimental data. Then, the dissertation concludes with future software and hardware upgrades for both synthetic and real MIR systems.
Download or read book Synthetic Diagnostic for the Evaluation of New Microwave Imaging Reflectometry System for Large Tokomaks DIII D and KSTAR written by Li Juan Lei and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Microwave Imaging Reflectometry (MIR) systems have been used as diagnostic tools for characterization of fluctuating plasma density in large tokamaks. Such a technique has been implemented on the TEXTOR device [H. Park, et al., Review of Scientific Instruments, 2004] and is being continued on DIII-D and KSTAR. To develop a new MIR system for density fluctuation measurements for DIII-D and KSTAR, one requires an understanding of how to preserve phase information. The current design for an MIR optical system makes use of design tools in free space, which is great for evaluation of port access but not provide significant information when it comes to the plasma region. This thesis describes a numerical study of MIR in the presence of turbulent fluctuations by evaluating the effectiveness in coupling the reflection layer in the full wave region and the detector array in free space with respect to fluctuation levels. A synthetic diagnostic tool making use of 2D full-wave diffractive simulation in full plasma geometry is applied to couple an optical imaging system with different optical arrangements.
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 Imaging Reflectometry MIR System for Plasma Turbulance Studies written by Jian Wang and published by . This book was released on 2004 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Design and Implementation of a Microwave Imaging Reflectometer MIR for the EAST Tokamak written by Xing Hu and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Nuclear fusion is one of the promising ways to generate renewable energy to solve the current energy crisis. However, controlled nuclear fusion with net power gain has not yet been achieved due to the instabilities inside the fusion plasmas. In order to control and eliminate these instabilities, diagnostic tools have been developed to understand the physics. Most of the characteristic frequencies of fusion plasmas fall within the millimeter wave region of the electromagnetic spectrum, which makes microwave imaging systems excellent tools for visualizing the particle activities inside fusion plasmas. There are two types of microwave imaging diagnostic systems developed at the Plasma Diagnostic Group at UC Davis: one is the electron cyclotron emission imaging (ECEI) system, which measures the ECE radiation from the plasma to determine electron temperature fluctuation and the other is the microwave imaging reflectometer (MIR), which injects multi-frequency probing beams into the plasma and measures the reflected beams from different cutoff surfaces to determine the electron density fluctuation. In this dissertation, the hardware setup of both ECEI and MIR systems is discussed. Characterization of the ECEI system for the HL-2A tokamak at Chengdu, China, and the MIR system for the DIII-D tokamak at La Jolla, USA, are given as an introduction to the laboratory testing methods of these microwave imaging systems. The topic of particular emphasis in this dissertation is the development of the latest generation MIR system for the EAST tokamak at Hefei, China. This system consists of 8 radial channels separated by different probing frequencies ranging from 75 to 103 GHz, and 12 vertically separated receiving channels, providing 96 imaging pixels inside the fusion plasma. As an important protection to the receiver system, development of the frequency selective surface based notch filter is discussed. The improved notch filter resonating at 140 GHz for the EAST MIR system has reduced the pass band insertion loss by half while maintaining over 30 dB rejection at the stop band. The implementation of embedded microcontrollers and RF components with serial peripheral interface (SPI) enables the system to be remotely controlled over the Ethernet. Technology advancements for future MIR systems including the CMOS based transmitter on chip and the digital beam forming technology are briefly discussed at the end of this dissertation.
Download or read book Issues in Applied Analytical and Imaging Sciences Research 2011 Edition written by and published by ScholarlyEditions. This book was released on 2012-01-09 with total page 1751 pages. Available in PDF, EPUB and Kindle. Book excerpt: Issues in Applied, Analytical, and Imaging Sciences Research: 2011 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Applied, Analytical, and Imaging Sciences Research. The editors have built Issues in Applied, Analytical, and Imaging Sciences Research: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Applied, Analytical, and Imaging Sciences Research 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 Applied, Analytical, and Imaging Sciences Research: 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/.
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 Broadband Reflectometry for Enhanced Diagnostics and Monitoring Applications written by Andrea Cataldo and published by Springer. This book was released on 2011-04-20 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is dedicated to the adoption of broadband microwave reflectometry (BMR)-based methods for diagnostics and monitoring applications. This electromagnetic technique has established as a powerful tool for monitoring purposes; in fact, it can balance several contrasting requirements, such as the versatility of the system, low implementation cost, real-time response, possibility of remote control, reliability, and adequate measurement accuracy. Starting from an extensive survey of the state of the art and from a clear and concise overview of the theoretical background, throughout the book, the different approaches of BMR are considered (i.e., time domain reflectometry - TDR, frequency domain reflectometry - FDR, and the TDR/FDR combined approach) and several applications are thoroughly investigated. The applications considered herein are very diverse from each other and cover different fields. In all the described procedures and methods, the ultimate goal is to endow them with a significant performance enhancement in terms of measurement accuracy, low cost, versatility, and practical implementation possibility, so as to unlock the strong potential of BMR.
Download or read book Microwave Imaging Radar Reflectometer Receiver System Utilizing Digital Beam Forming written by Fengqi Hu and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, the exponentially increasing energy requirements and the serious environmental problems caused by traditional fossil sources have drawn tremendous attention to the development of alternative energy sources. One of the most promising candidates is nuclear fusion energy. To study the fundamental physical phenomena inside the confined hot plasma of which the temperatures are in excess of 100 million Kelvin, advanced imaging systems are being developed with millimeter wave imaging systems of particular importance. The Microwave Imaging Reflectometry (MIR) developed at UC Davis is an active radar imaging system used to measure the electron density fluctuations. In the currently employed system, carefully designed optical lenses are used to shape the probing beam so that it would impinge upon the plasma cutoff surface with normal incidence. On the receiver side, another set of lenses are used to collect and further shape the beam to form an image of the cutoff surface. The focusing is done by motor controlled lenses, which not only take up more space but also are slow to adjust compared to many plasma times of interest. Phased array synthesis offers the ability to change the shaping and steering of the beam electronically for fast-tracking and remote tuning without the need for bulky lenses. Based on where in the system the phase shifting is performed, there are two major categories of phased array. One is the analog phased array where the beam shaping and steering are done in the analog domain with analog phase shifters. The other approach is digital beamforming where the amplitude scaling and the phase shifting are realized by mathematical operations in the digital domain. Compared to its analog counterpart, digital beam forming could be done much faster with great flexibility. The focus of this dissertation is the utilization of digital beam forming to realize high speed focusing with greater flexibility. The beam shaping, focusing/de-focusing, beam steering and beam translation with digital beam forming are demonstrated with a simplified W-band receiver system. The possibility of a V-band system-on-substrate with on-board LO feed is also explored.
Download or read book Nuclear Fusion written by and published by . This book was released on 2006-12 with total page 632 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Magnetic Fusion Technology written by Thomas J. Dolan and published by Springer Science & Business Media. This book was released on 2014-02-10 with total page 816 pages. Available in PDF, EPUB and Kindle. Book excerpt: Magnetic Fusion Technology describes the technologies that are required for successful development of nuclear fusion power plants using strong magnetic fields. These technologies include: • magnet systems, • plasma heating systems, • control systems, • energy conversion systems, • advanced materials development, • vacuum systems, • cryogenic systems, • plasma diagnostics, • safety systems, and • power plant design studies. Magnetic Fusion Technology will be useful to students and to specialists working in energy research.
Download or read book Applications of GNSS Reflectometry for Earth Observation written by Nereida Rodriguez-Alvarez and published by Mdpi AG. This book was released on 2021-11-24 with total page 496 pages. Available in PDF, EPUB and Kindle. Book excerpt: Global Navigation Satellite System-Reflectometry (GNSS-R) has proven an effective and very valuable technique that has helped the scientific community to better understand Earth processes. Measuring the forward scattering that occurs when the Global Positioning System (GPS) signals reflect off the surface of the Earth has enabled multiple studies of the ocean, the cryosphere, and the land geophysical phenomena, allowing a better characterization and increasing the global knowledge of our planet. This book brings together a variety of the most up-to-date research on the GNSS-R field, covering multiple and very innovative applications.
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 Waves and Instabilities in Plasmas written by F. Cap and published by Springer. This book was released on 2014-05-04 with total page 287 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book presents the contents of a CISM Course on waves and instabilities in plasmas. For beginners and for advanced scientists a review is given on the state of knowledge in the field. Customers can obtain a broad survey.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1983-07 with total page 616 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Polymer Characterisation written by B.J. Hunt and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 376 pages. Available in PDF, EPUB and Kindle. Book excerpt: Polymers continue to play an ever increasing role in the modern world. In fact it is quite inconceivable to most people that we could ever have existed of the increased volume and variety of materials without them. As a result currently available, and the diversity of their application, characterisation has become an essential requirement of industrial and academic laboratories in volved with polymeric materials. On the one hand requirements may come from polymer specialists involved in the design and synthesis of new materials who require a detailed understanding of the relationship between the precise molecular architecture and the properties of the polymer in order to improve its capabilities and range of applications. On the other hand, many analysts who are not polymer specialists are faced with the problems of analysing and testing a wide range of polymeric materials for quality control or material specification purposes. We hope this book will be a useful reference for all scientists and techno or industrial laboratories, logists involved with polymers, whether in academic and irrespective of their scientific discipline. We have attempted to include in one volume all of the most important techniques. Obviously it is not possible to do this in any great depth but we have encouraged the use of specific examples to illustrate the range of possibilities. In addition numerous references are given to more detailed texts on specific subjects, to direct the reader where appropriate. The book is divided into II chapters.
Download or read book Apatites and their Synthetic Analogues written by Petr Ptáček and published by BoD – Books on Demand. This book was released on 2016-04-13 with total page 516 pages. Available in PDF, EPUB and Kindle. Book excerpt: Apatite-type minerals and their synthetic analogues are of interest of many industrial branches and scientific disciplines including material sciences, chemical industry, agriculture, geology, medicine and dentistry. This book provides a basic overview of general knowledges of this topic in order to provide the comprehensive survey from a scientific and technological perspective. The book is divided into 10 chapters, which are devoted to the structure and properties of minerals from the supergroup of apatite, experimental techniques of preparation and characterization of synthetic analogues of apatite minerals, substitution in the structure of apatite as well as utilization of these materials in wide range of common and special advanced applications in industry, material sciences and research. Additionally, the phosphate rocks, their classification, geological role, mining and beneficiation of phosphate ore, production of elemental phosphorus, phosphoric acid and fertilizers are also described. Although this book is meant for chemist, material scientist and research engineers, the individual chapters contain theoretical background, historical aspects as well as examples of synthetic and analytical methods which may be also interesting for students and non-expert readers as well.
