Read Books Online and Download eBooks, EPub, PDF, Mobi, Kindle, Text Full Free.
Comprehensive Measurements And Modeling Of Sol And Core Plasma Fueling And Carbon Sources In Diii D
Download Comprehensive Measurements And Modeling Of Sol And Core Plasma Fueling And Carbon Sources In Diii D full books in PDF, epub, and Kindle. Read online Comprehensive Measurements And Modeling Of Sol And Core Plasma Fueling And Carbon Sources In Diii D ebook anywhere anytime directly on your device. Fast Download speed and no annoying ads. We cannot guarantee that every ebooks is available!
Book Synopsis Comprehensive Measurements and Modeling of SOL, and Core Plasma Fueling and Carbon Sources in DIII-D. by : J. Watkins
Download or read book Comprehensive Measurements and Modeling of SOL, and Core Plasma Fueling and Carbon Sources in DIII-D. written by J. Watkins and published by . This book was released on 2005 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasma boundary modeling of low density, low confinement plasmas in DIII-D has been benchmarked against a comprehensive set of measurements and indicates that recycling of deuterium ions at the divertor targets, and chemical sputtering at the divertor target plates and walls, can explain the poloidal core fueling profile and core carbon density. Key measurements included the 2-D intensity distribution of deuterium neutral and low-charge state carbon emission in the divertor and around the midplane of the high-field scrape-off layer (SOL). Chemical sputtering plays an important role in producing carbon at the divertor targets and walls, and was found to be a prerequisite to reproduce the measured emission distribution.
Book Synopsis Protokoll über die Verhandlungen des Vereinigungs-Gewerkschaftstages der Industriegewerkschaft Nahrung, Genuss, Gaststätten für das Gebiet der amerikanisch, britisch und französisch besetzten Zonen Deutschlands in München vom 24. bis 26. Mai 1949 by :
Download or read book Protokoll über die Verhandlungen des Vereinigungs-Gewerkschaftstages der Industriegewerkschaft Nahrung, Genuss, Gaststätten für das Gebiet der amerikanisch, britisch und französisch besetzten Zonen Deutschlands in München vom 24. bis 26. Mai 1949 written by and published by . This book was released on 1949 with total page 272 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Implications of Wall Recycling and Carbon Source Locations on Core Plasma Fueling and Impurity Content in DIII-D. by : J. G. Watkins
Download or read book Implications of Wall Recycling and Carbon Source Locations on Core Plasma Fueling and Impurity Content in DIII-D. written by J. G. Watkins and published by . This book was released on 2004 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt: Measurement and modeling of the 2-D poloidal D{alpha} intensity distribution in DIII-D low and medium density L-mode and ELMy H-mode plasmas indicate that hydrogen neutrals predominantly fuel the core from the divertor X-point region. The 2-D distribution of neutral deuterium and low-charge-state carbon were measured in the divertor and the high-field side midplane scrape-off layer (SOL) using tangentially viewing cameras. The emission in the high-field SOL at the equatorial plane was found to be three to four orders of magnitude lower than at the strike points in the divertor, suggesting a strong divertor particle source. Modeling using the UEDGE/DEGAS codes predicted the poloidal fueling distribution to be dependent on the direction of the ion Bx{Delta}B drift. In plasmas with the Bx{Delta}B drift into the divertor stronger fueling from the inner divertor than from the outer is predicted, due to a lower-temperature and higher-density plasma in the inner leg. UEDGE simulations with carbon produced by both physical and chemical sputtering at the divertor plates and walls only are in agreement with a large set of diagnostic data. The simulations indicate flow reversal in the inner divertor that augments the leakage of carbon ions from the divertor into the core.
Book Synopsis Implications of Wall Recycling and Carbon Source Locations on Core Plasma Fueling and Impurity Content in DIII-D. by :
Download or read book Implications of Wall Recycling and Carbon Source Locations on Core Plasma Fueling and Impurity Content in DIII-D. written by and published by . This book was released on 2004 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Plasma Surface Interactions in Controlled Fusion Devices by :
Download or read book Plasma Surface Interactions in Controlled Fusion Devices written by and published by . This book was released on 1978 with total page 658 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Carbon Influx in He and D Plasmas in DIII-D. by :
Download or read book Carbon Influx in He and D Plasmas in DIII-D. written by and published by . This book was released on 1998 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt: Differences in the carbon behavior between He and D plasmas during VH-mode, L-mode and L-mode with excess gas puffing are reported and inferences on the importance of the various carbon sources during these modes of operation are discussed. During a VH-mode phase, VUV and visible charge exchange spectroscopy indicates that for both He and D operation the carbon behavior is very similar. In the edge plasma, carbon build up is quite rapid, and the carbon influx represents a large fraction of the total plasma density increase until the termination of the VH phase. During cold divertor operation induced by puffing the primary fueling gas, D and He discharges show a difference in the carbon behavior. The core carbon density is seen to be approximately constant during a D discharge as it transitions from an attached to a cold divertor. However in a He discharge, the core carbon density disappears soon after the cold divertor transition. Arguments are made that the primary carbon source in the ELM free H-mode period is physical sputtering by ion impact at the divertor strike point. In L-mode, both attached and cold divertor, the primary source is from the divertor region and two possibilities for this source are chemical sputtering or charge neutral sputtering. Existing data supports charge exchange neutrals as dominant.
Book Synopsis Comprehensive Dynamic Analysis of the H-Mode Pedestal in DIII-D. by : Andrew Oakleigh Nelson
Download or read book Comprehensive Dynamic Analysis of the H-Mode Pedestal in DIII-D. written by Andrew Oakleigh Nelson and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The H-mode pedestal, characterized by steep gradients and reduced transport, is an essential feature of tokamak plasmas that couples the cold Scrape-Off-Layer (SOL) to the hot, fusion-relevant core. Though existing magnetohydrodynamic models yield some insight into the pedestal, they are (due to the complexity of interaction between the pedestal and the rest of the plasma) unable to fully predict pedestal behavior from generalized plasma conditions. To progress towards a more comprehensive understanding of pedestal dynamics, a larger context must be considered. Using state-of-the-art modeling and perturbative experimental techniques on DIII-D, this thesis develops a broader empirical understanding of dynamic pedestal behavior that will inform future modeling efforts.The pedestal obeys the physics of the continuity equation, which is set by the sourcing of particles, inter-ELM transport, and boundary conditions. In this light, three phenomena are selected for in-depth study: fueling, transport, and SOL interactions. First, the effect of particle sources on the pedestal structure is examined through a series of dedicated experiments on DIII-D. Gas and pellet fueling techniques are applied to change the neutral ionization profile at similar plasma conditions, showing that the structure of the pedestal can vary significantly with changes to the neutral source profile. Second, a novel experimental technique is used to probe the nature of inter-ELM turbulence, which is linked to the evolution and recovery of the pedestal structure. Additional current is induced in the pedestal region of several DIII-D plasmas, providing a first-of-its-kind experimental demonstration of microtearing modes (MTMs) in the tokamak edge. MTMs may contribute strongly to intense heat fluxes through the pedestal region, potentially providing the groundwork for an entirely physics-based predictive model of pedestal behavior. Finally, to develop a physics understanding of how the SOL boundary condition couples with the pedestal over the course of an entire plasma discharge, detailed modeling work is performed with the UEDGE code as a function of pedestal and ELM conditions. In this section, we establish a dynamic connection between the pedestal structure and divertor behavior, highlighting the need for a comprehensive approach to pedestal physics.
Book Synopsis Database Needs for Modeling and Simulation of Plasma Processing by : National Research Council
Download or read book Database Needs for Modeling and Simulation of Plasma Processing written by National Research Council and published by National Academies Press. This book was released on 1996-10-21 with total page 74 pages. Available in PDF, EPUB and Kindle. Book excerpt: In spite of its high cost and technical importance, plasma equipment is still largely designed empirically, with little help from computer simulation. Plasma process control is rudimentary. Optimization of plasma reactor operation, including adjustments to deal with increasingly stringent controls on plant emissions, is performed predominantly by trial and error. There is now a strong and growing economic incentive to improve on the traditional methods of plasma reactor and process design, optimization, and control. An obvious strategy for both chip manufacturers and plasma equipment suppliers is to employ large-scale modeling and simulation. The major roadblock to further development of this promising strategy is the lack of a database for the many physical and chemical processes that occur in the plasma. The data that are currently available are often scattered throughout the scientific literature, and assessments of their reliability are usually unavailable. Database Needs for Modeling and Simulation of Plasma Processing identifies strategies to add data to the existing database, to improve access to the database, and to assess the reliability of the available data. In addition to identifying the most important needs, this report assesses the experimental and theoretical/computational techniques that can be used, or must be developed, in order to begin to satisfy these needs.
Book Synopsis Divertor Plasma Studies on DIII-D by :
Download or read book Divertor Plasma Studies on DIII-D written by and published by . This book was released on 1996 with total page 33 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a magnetically diverted tokamak, the scrape-off layer (SOL) and divertor plasma provides separation between the first wall and the core plasma, intercepting impurities generated at the wall before they reach the core plasma. The divertor plasma can also serve to spread the heat and particle flux over a large area of divertor structure wall using impurity radiation and neutral charge exchange, thus reducing peak heat and particle fluxes at the divertor strike plate. Such a reduction will be required in the next generation of tokamaks, for without it, the divertor engineering requirements are very demanding. To successfully demonstrate a radiative divertor, a highly radiative condition with significant volume recombination must be achieved in the divertor, while maintaining a low impurity content in the core plasma. Divertor plasma properties are determined by a complex interaction of classical parallel transport, anomalous perpendicular transport, impurity transport and radiation, and plasma wall interaction. In this paper the authors describe a set of experiments on DIII-D designed to provide detailed two dimensional documentation of the divertor and SOL plasma. Measurements have been made in operating modes where the plasma is attached to the divertor strike plate and in highly radiating cases where the plasma is detached from the divertor strike plate. They also discuss the results of experiments designed to influence the distribution of impurities in the plasma using enhanced SOL plasma flow. Extensive modeling efforts will be described which are successfully reproducing attached plasma conditions and are helping to elucidate the important plasma and atomic physics involved in the detachment process.
Book Synopsis UEDGE and DEGAS Modeling of the DIII-D Scrape-off Layer Plasma. Revision 1 by :
Download or read book UEDGE and DEGAS Modeling of the DIII-D Scrape-off Layer Plasma. Revision 1 written by and published by . This book was released on 1994 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents work to develop benchmarked theoretical models of scrape-off-layer (SOL) characteristics in diverted tokamaks by comparing shot simulations using the UEDGE plasma fluid and DEGAS neutral transport codes to measurements of the DIII-D SOL plasma. The experimental data include the radial profiles of n{sub e} T{sub e}, and T{sub i}, the divertor exhaust power, the intensity of H{sub {alpha}} emission, and profiles of the radiated power. A very simple model of the anomalous perpendicular transport rates produces consistency between the calculated and measured radial profiles of the divertor power, and of the midplane densities and temperatures. Experimentally, the measured exhaust power is now 80--90% of the input power. The simulated peak power on the outer leg of the divertor floor is now within 20% of the measured power. Various sensitivities of these comparisons to model assumptions are described. Finally, these benchmarked models have been used to examine the effects of various baffle configurations for the Radiative Divertor Upgrade in DIII-D.
Book Synopsis Measurement of Molecular Deuterium Fluxes in the DIII-D Edge by : A. McLean
Download or read book Measurement of Molecular Deuterium Fluxes in the DIII-D Edge written by A. McLean and published by . This book was released on 2005 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: In hydrogen-fueled tokamak discharges, the distribution of molecular hydrogen (or deuterium) in the plasma edge region plays a central role in edge fueling, affecting pedestal shape and core density control [1]. In addition to its role in edge fueling, molecular hydrogen is important for plasma edge atomic physics. An example of this is the enhancement of plasma volume recombination known to occur in the presence of vibrationally-excited hydrogen molecules via conversion of H{sup +} ions into molecular ions such as H{sub 2}{sup +} and H{sub 3}{sup +} [2]. Here, measurements of the D{sub 2} molecule flux into the far edge/scrape-off layer (SOL) of the DIII-D tokamak are made using passive visible spectroscopy of the D{sub 2} diagonal Fulcher band (3p-2s triplet Q-branch) line emission over the range {lambda} = 600.640 nm [3]. L-mode, lower-single-null discharges are studied. A multi-chord visible spectrometer with views of both lower divertor legs and the main chamber is used [4]. A schematic of the spectrometer view chords used here, as well as typical magnetic flux surfaces, midplane probe location, and Thomson scattering view locations, are shown in Fig. 1. As a convenient variable to describe the location of each view chord, the poloidal angle {theta} of the corresponding emission volume is used (Fig. 1). Each view chord crosses the SOL twice; in the case of the upper view chords and lower view chords, the emission from the SOL closer to the lower divertor is expected to dominate the measured signal. In the case of the midplane view chord, lineshape (Zeeman splitting) analysis of the D{sub {alpha}} line indicates that the received emission is typically dominated by the inner wall SOL (over the outer wall SOL by {approx} 2-8x).
Book Synopsis DIII-D Experiments and Modeling of Core Confinement in Quiescent Double Barrier Plasmas by :
Download or read book DIII-D Experiments and Modeling of Core Confinement in Quiescent Double Barrier Plasmas written by and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We continue to explore Quiescent Double Barrier (QDB) operation on DIII-D to address issues of critical importance to internal transport barrier (ITB) plasmas. QDB plasmas exhibit both a core transport barrier and a quiescent, H-mode edge barrier. Both experiments and modeling of these plasmas are leading to an increased understanding of this regime and it's potential advantages for advanced-tokamak (AT) burning-plasma operation. These near steady plasma conditions have been maintained on DIII-D for up to 4s, times greater than 35[tau][sub E], and exhibit high performance with [beta][sub N]> 2.5 and neutron production rates S[sub n] [approx] 1 x 10[sup 16]s[sup -1]. Recent experiments have been directed at exploring both the current profile modification effects of electron cyclotron current drive (ECCD) and electron cyclotron (ECH) heating-induced changes in temperature, density and impurity profiles. We use model-based analysis to determine the effects of both heating and current drive on the q-profile in these QDB plasmas. Experiments based on predictive modeling achieved a significant modification to the q-profile evolution [1] resulting from the non-inductive current drive effects due to direct ECCD and changes in the bootstrap and neutral beam current drive components. We observe that the injection of EC power inside the barrier region changes the density peaking from n[sub e]/n[sub e] = 2.1 to 1.5 accompanied by a significant reduction in the core carbon and high-Z impurities, nickel and copper.
Book Synopsis UEDGE and DEGAS Modeling of the DIII-D Scrape-off Layer Plasma by :
Download or read book UEDGE and DEGAS Modeling of the DIII-D Scrape-off Layer Plasma written by and published by . This book was released on 1994 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: This paper presents the results of work to develop benchmarked theoretical models of scrape-off-layer (SOL) characteristics in diverted tokamaks by comparing shot simulations using the UEDGE plasma fluid and DEGAS Monte-Carlo neutral particle transport codes to measurements of the DIII-D SOL plasma. The available experimental data include the radial profiles of electron density and temperature, the ion temperature, the divertor exhaust power, the intensity of H{sub {alpha}} emission, and profiles of the radiated power. A very simple model of the anomalous perpendicular transport rates produces consistency between the calculated and measured radial profiles of the divertor power, and of the midplane densities and temperatures. Experimentally, measured exhaust power is now typically 80--90% of the input power. The simulated peak power on the outer leg of the divertor floor is now within about 20% of the measured power. Various sensitivities of the simulation and measurement comparisons to model assumptions are described. Finally, these benchmarked models have been used to examine the effects of various baffle configurations for the Radiative Divertor Upgrade in DIII-D.
Book Synopsis Developing Models for the DIII-D Boundary Plasma by :
Download or read book Developing Models for the DIII-D Boundary Plasma written by and published by . This book was released on 2005 with total page 50 pages. Available in PDF, EPUB and Kindle. Book excerpt: Development of the comprehensive codes used to study the boundary region of the DIII-D tokamak has been done in parallel with improvement of the diagnostics of this important region of the plasma. These codes have been used to interpret the diagnostic data and assist in design of improved divertor configurations. The development of codes used for analysis on DIII-D is described briefly. Model validation by comparing with the extensive DIII-D boundary region diagnostic data is also discussed.
Book Synopsis DIII-D Experiments and Modeling of Core Confinement in Quiescent Double Barrier Plasmas by : T. H. Osborne
Download or read book DIII-D Experiments and Modeling of Core Confinement in Quiescent Double Barrier Plasmas written by T. H. Osborne and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We continue to explore Quiescent Double Barrier (QDB) operation on DIII-D to address issues of critical importance to internal transport barrier (ITB) plasmas. QDB plasmas exhibit both a core transport barrier and a quiescent, H-mode edge barrier. Both experiments and modeling of these plasmas are leading to an increased understanding of this regime and it's potential advantages for advanced-tokamak (AT) burning-plasma operation. These near steady plasma conditions have been maintained on DIII-D for up to 4s, times greater than 35{tau}{sub E}, and exhibit high performance with {beta}{sub N}> 2.5 and neutron production rates S{sub n} {approx} 1 x 10{sup 16}s{sup -1}. Recent experiments have been directed at exploring both the current profile modification effects of electron cyclotron current drive (ECCD) and electron cyclotron (ECH) heating-induced changes in temperature, density and impurity profiles. We use model-based analysis to determine the effects of both heating and current drive on the q-profile in these QDB plasmas. Experiments based on predictive modeling achieved a significant modification to the q-profile evolution [1] resulting from the non-inductive current drive effects due to direct ECCD and changes in the bootstrap and neutral beam current drive components. We observe that the injection of EC power inside the barrier region changes the density peaking from n{sub e}/n{sub e} = 2.1 to 1.5 accompanied by a significant reduction in the core carbon and high-Z impurities, nickel and copper.
Book Synopsis Particle Flows in Pumped DIII-D Discharges by :
Download or read book Particle Flows in Pumped DIII-D Discharges written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The dynamics of particle flows in the DIII-D tokamak for two divertor configurations is considered. Fuel and intrinsic carbon impurity flows are analyzed using experimental data and 2D fluid plasma simulations. The flows in puff and pump experiments done in an open and a closed divertor geometry are described. It is shown that the flow of fuel particles is sensitive to divertor geometry. The pumping efficiency of the DIII-D cryopumps is a factor of 2 higher in a closed geometry than an open. The core refueling rate of an open divertor is a factor of 2 higher than that of a closed divertor. In contrast, the flow of impurity carbon particles is insensitive to divertor geometry. Both the core carbon content and the fraction of the carbon source which penetrates to the core is unchanged between an open and closed divertor. In addition, the core impurity content is found to be insensitive to the amplitude of gas puffing in the simulations.
Book Synopsis Modeling the Neutral Density in the Edge of the DIII-D Plasma by : Weston Monroe Stacey
Download or read book Modeling the Neutral Density in the Edge of the DIII-D Plasma written by Weston Monroe Stacey and published by . This book was released on 1999 with total page 22 pages. Available in PDF, EPUB and Kindle. Book excerpt:
