Development and Applications of Synthetic Microwave Imaging Reflectometry (MIR) Diagnostics PDF Download

Author: Xiaoxin Ren
Publisher:
ISBN: 9781369201437
Category :
Languages : en
Pages :

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Book Description
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.

Author: Ming Chen
Publisher:
ISBN: 9780438290617
Category :
Languages : en
Pages :

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Book Description
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.

Author: Jian Wang
Publisher:
ISBN:
Category :
Languages : en
Pages : 196

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Author:
Publisher: ScholarlyEditions
ISBN: 1464964114
Category : Science
Languages : en
Pages : 1751

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Book Description
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/.

Author: Andrea Cataldo
Publisher: Springer
ISBN: 9783642202346
Category : Technology & Engineering
Languages : en
Pages : 150

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Book Description
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.

Author: Fengqi Hu
Publisher:
ISBN: 9780355149494
Category :
Languages : en
Pages :

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Book Description
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.

Author:
Publisher:
ISBN:
Category : Electronic journals
Languages : en
Pages : 632

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Author: Nereida Rodriguez-Alvarez
Publisher: Mdpi AG
ISBN: 9783036520667
Category : Science
Languages : en
Pages : 496

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Book Description
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.

Author: Thomas J. Dolan
Publisher: Springer Science & Business Media
ISBN: 1447155564
Category : Technology & Engineering
Languages : en
Pages : 816

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Book Description
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.

Author: Ernesto Mazzucato
Publisher: World Scientific
ISBN: 9814571822
Category : Science
Languages : en
Pages : 223

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Book Description
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.