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 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 Simultaneous Microwave Imaging System for Density and Temperature Fluctuation Measurements on TEXTOR written by Hyeon Keo Park and published by . This book was released on 2004 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 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 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 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 Microwave Imaging Reflectometry for the Visualization of Turbulence in Tokamaks written by E. Mazzucato and published by . This book was released on 1999 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 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 for the Measurement of Turbulent Fluctuations in Tokamaks written by E. Mazzucato and published by . This book was released on 2004 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laboratory Characterization of an Imaging Reflectometer System written by Tobin Leo Munsat and published by . This book was released on 2003 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microwave Imaging Reflectometer Down conversion Electronics for DIII D and EAST Tokamak Fusion Reactors written by Alexander Grenbeaux Spear and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Increasing worldwide energy demand has necessitated the building of more power generation facilities. These facilities often consume pollution emitting fossil fuels (coal, gas, etc.) or generate dangerous radioactive byproducts (nuclear fission). Much research has been done to find new, more environmentally conscious ways of providing energy; some of which are promising. An outstanding candidate for clean energy production is nuclear fusion; the process of binding atoms together to release energy in the same process stars use to power the universe. Nuclear fusion can provide clean reliable energy with an almost inexhaustible fuel supply: Hydrogen. However, commercial fusion power cannot start without first understanding the complex processes occurring within burning (self-perpetuating) plasmas. Multiple fusion research reactors have been built around the world to study plasma behavior. The most promising reactor types for the advancement of commercial fusion are Tokamaks.Plasmas which exist in fusion reactors can reach temperatures in the many millions of Kelvin. Microwave and milli-meter wave diagnostic devices provide the capability to monitor various plasma parameters and visualize plasma phenomena without requiring direct contact with the plasma. Outlined in this dissertation are two different Microwave Imaging Reflectometer (MIR) systems designed for the DIII-D and EAST Tokamak fusion reactors. Reflectometry is a technique by which radio frequency (RF) signals are transmitted into the plasma and the reflection phase and amplitude is measured. Special imaging optics are employed to focus the sampled plasma volume onto the RF detector arrays to enhance signal coherence. The Super-Heterodyne down-conversion electronics of the presented MIR systems are highlighted.

Download or read book Microwave millimeter wave Beam Steering shaping Phased Antenna Arrays and Planar Imaging Antenna Arrays for Plasma Diagnostic Application written by Lu Yang and published by . This book was released on 2007 with total page 348 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Laboratory Characterization of an Imaging Reflectometer System written by Tobin Leo Munsat and published by . This book was released on 2003 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Microwave Reflectometry for Magnetically Confined Plasmas written by E. Mazzucato and published by . This book was released on 1998 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Simulation of Optical and Synthetic Imaging Using Microwave Reflectometry written by G. J. Kramer and published by . This book was released on 2004 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: