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 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 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 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 Plasma Diagnostics with Microwaves written by Mark A. Heald and published by . This book was released on 1978 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 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 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 Advanced Diagnostics for Magnetic and Inertial Fusion written by Peter E. Stott and published by Springer Science & Business Media. This book was released on 2011-06-28 with total page 449 pages. Available in PDF, EPUB and Kindle. Book excerpt: Proceedings of the International Conference on Advanced Diagnostics for Magnetic and Inertial Fusion, held September 3-7, 2001 at Villa Monastero, Varenna, Italy. This volume focuses on future diagnostic requirements for fusion energy research emphasizing advanced diagnostics, new techniques and areas where further progress is required.

Download or read book Millimeter Wave Imaging Technologies for Plasma Diagnostics on Superconducting Tokomak Machines written by Zuowei Shen and published by . This book was released on 2007 with total page 438 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 Fusion Plasma Diagnostics with mm Waves written by Hans-Jürgen Hartfuß and published by John Wiley & Sons. This book was released on 2013-11-04 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Filling a gap in the literature, this introduction to the topic covers the physics of the standard microwave diagnostics established on modern fusion experiments, and the necessary technological background from the field of microwave engineering. Written by well-known mm-wave diagnosticians in the field of fusion physics, the textbook includes such major diagnostic techniques as electron cyclotron emission, interferometry, reflectometry, polarimetry, and scattering.

Download or read book Topics in Plasma Diagnostics written by I. Podgornyi and published by Springer. This book was released on 1971 with total page 240 pages. Available in PDF, EPUB and Kindle. Book excerpt: The present volume is essentially a qualitative survey of modern trends in the diagnostics of high-temperature plasmas, with particular orientation toward laboratory plasmas of interest in connection with research in controlled thermonuclear fusion. Among the broad topics considered are probe diagnostics, optical methods (including the use of lasers and holography), microwave diagnostics, and diagnostics with particle beams. Having infor mation on these methods available in compact form and in one place, as is the case in the present volume, should make it pos sible to evaluate different diagnostic approaches to specific prob lems. The volume will be useful as an introduction for advanced students making their first contact with experimental plasma physics and for physicists and engineers who are entering the field and desire a rapid survey of principles and modern trends in the diagnostics of high-temperature plasmas. v Foreword to the American Edition The material in this book is based on lectures given at Mos cow State University. It is intended to acquaint the reader with the basic aspects of plasma diagnostics and contains information re quired for the experimental physicist who wishes to carry out straightforward measurements of laboratory plasmas. It will be evident that in choosing the material we have been guided pri marily by the scientific interests of the author, and the great bulk of the material is based on work carried out in the USSR.

Download or read book Some Measurements of Steady and Fluctuating Plasma Number Densities by a Microwave Method written by Stanford University. Microwave Laboratory and published by . This book was released on 1962 with total page 68 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 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.