Scrape-Off Layer Transport and Deposition Studies in DIII-D. PDF Download
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Author: S. Allen
Publisher:
ISBN:
Category :
Languages : en
Pages : 51
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Book Description
Trace {sup 13}CH{sub 4} injection experiments into the main scrape-off layer of low density L-mode and high-density H-mode plasmas have been performed in the DIII-D tokamak [Luxon{_}NF02] to mimic the transport and deposition of carbon arising from a main chamber sputtering source. These experiments indicated entrainment of the injected carbon in plasma flow in the main SOL, and transport toward the inner divertor. Ex-situ surface analysis showed enhanced {sup 13}C surface concentration at the corner formed by the divertor floor and the angled target plate of the inner divertor in L-mode; in H-mode, both at the corner and along the surface bounding the private flux region inboard of the outer strike point. Interpretative modeling was made consistent with these experimental results by imposing a parallel carbon ion flow in the main SOL toward the inner target, and a radial pinch toward the separatrix. Predictive modeling carried out to better understand the underlying plasma transport processes suggests that the deuterium flow in the main SOL is related to the degree of detachment of the inner divertor leg. These simulations show that carbon ions are entrained with the deuteron flow in the main SOL via frictional coupling, but higher charge state carbon ions may be suspended upstream of the inner divertor X-point region due to balance of the friction force and the ion temperature gradient.
Author: S. Allen
Publisher:
ISBN:
Category :
Languages : en
Pages : 51
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Book Description
Trace {sup 13}CH{sub 4} injection experiments into the main scrape-off layer of low density L-mode and high-density H-mode plasmas have been performed in the DIII-D tokamak [Luxon{_}NF02] to mimic the transport and deposition of carbon arising from a main chamber sputtering source. These experiments indicated entrainment of the injected carbon in plasma flow in the main SOL, and transport toward the inner divertor. Ex-situ surface analysis showed enhanced {sup 13}C surface concentration at the corner formed by the divertor floor and the angled target plate of the inner divertor in L-mode; in H-mode, both at the corner and along the surface bounding the private flux region inboard of the outer strike point. Interpretative modeling was made consistent with these experimental results by imposing a parallel carbon ion flow in the main SOL toward the inner target, and a radial pinch toward the separatrix. Predictive modeling carried out to better understand the underlying plasma transport processes suggests that the deuterium flow in the main SOL is related to the degree of detachment of the inner divertor leg. These simulations show that carbon ions are entrained with the deuteron flow in the main SOL via frictional coupling, but higher charge state carbon ions may be suspended upstream of the inner divertor X-point region due to balance of the friction force and the ion temperature gradient.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 48
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Book Description
We are in the process of assembling a database of edge and divertor plasma parameters suitable for use in benchmarking tious 2D models of the scrape-off- layer (SOL) plasma. Also, we are using the Braams B2 code to derive transport coefficients for the edge plssma. In parallel, work is starting on an upgrade to the B2 code that includes padlel current flow and EXB drifts. These efforts are directed at increasing the confidence level of models of the tokamak edge plasma so that we can predict the effect of planned upgrades to DIII-D (e.g., the Advanced Divertor Program) and the performance of next generation machines such as CIT or ITER, where initial design studies show that plasma conditions at the divertor targets can have a large impact on the lifetime and cost of the machine. This report summarizes our recent progress in characterizing the DIII-D SOL plasma and in modeling these data with the the B2 code. Section I contains a brief description of the diagnostics available for characterizing the SOL plasma. In Section II we present our measurements of the SOL parameters for H-mode plasmas. This includes data showing how the divertor plasma parameters (n{sub e}(r), T{sub e}(r), and Q(r)) vary from ohmic to L-mode to H-mode, and power balance for quasi-stationary H-mode plasmas. Section III covers divertor-target heat-flux asymmetries for double and single null operation with forward and reversed toroidal field. In Section IV we show the scaling of L-mode parameters with neutral beam power, and Section V concludes with a summary of the results obtained from the Braams B2 SOL simulation code.
Author: Francisco L. Tabarés
Publisher: CRC Press
ISBN: 1000245276
Category : Science
Languages : en
Pages : 317
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Book Description
This book is an up-to-date review of the most important plasma-based techniques for material modification, from microelectronics to biological materials and from fusion plasmas to atmospheric ones. Each its technical chapters is written by long-experienced, internationally recognised researchers. The book provides a deep and comprehensive insight into plasma technology and its associated elemental processes and is illustrated throughout with excellent figures and references to complement each section. Although some of the topics covered can be traced back several decades, care has been taken to emphasize the most recent findings and expected evolution. The first time the word ‘plasma’ appeared in print in a scientific text related to the study of electrical discharges in gases was 1928, when Irving Langmuir published his article ‘Oscillations in Ionized Gases’. It was the baptism of the predominant state of matter in the known universe (it is estimated that up to 99% of matter is plasma), although not on earth, where the conditions of pressure and temperature make normal the states of matter (solid, liquid, gas) which, in global terms, are exotic. It is enough to add energy to a solid (in the form of heat or electromagnetic radiation) to go into the liquid state, from which gas is obtained through an additional supply of energy. If we continue adding energy to the gas, we will partially or totally ionise it and reach a new state of matter, plasma, made up of free electrons, atoms and molecules (electrically neutral particles) and ions (endowed with a positive or a negative electric charge).
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
The scientific goal of the UCSD-DIII-D Collaboration during this period was to understand the coupling of the core plasma to the plasma-facing components through the plasma boundary (edge and scrape-off layer). To achieve this goal, UCSD scientists studied the transport of particles, momentum, energy, and radiation from the plasma core to the plasma-facing components under normal (e.g., L-mode, H-mode, and ELMs), and off-normal (e.g., disruptions) operating conditions.
Author:
Publisher:
ISBN:
Category : Aeronautics
Languages : en
Pages : 994
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Book Description
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: National Academies of Sciences, Engineering, and Medicine
Publisher: National Academies Press
ISBN: 0309487439
Category : Science
Languages : en
Pages : 341
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Book Description
Fusion offers the prospect of virtually unlimited energy. The United States and many nations around the world have made enormous progress toward achieving fusion energy. With ITER scheduled to go online within a decade and demonstrate controlled fusion ten years later, now is the right time for the United States to develop plans to benefit from its investment in burning plasma research and take steps to develop fusion electricity for the nation's future energy needs. At the request of the Department of Energy, the National Academies of Sciences, Engineering, and Medicine organized a committee to develop a strategic plan for U.S. fusion research. The final report's two main recommendations are: (1) The United States should remain an ITER partner as the most cost-effective way to gain experience with a burning plasma at the scale of a power plant. (2) The United States should start a national program of accompanying research and technology leading to the construction of a compact pilot plant that produces electricity from fusion at the lowest possible capital cost.
Author: National Academies of Sciences, Engineering, and Medicine
Publisher: National Academies Press
ISBN: 0309469333
Category : Science
Languages : en
Pages : 61
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Book Description
In January 2003, President George W. Bush announced that the United States would begin negotiations to join the ITER project and noted that "if successful, ITER would create the first fusion device capable of producing thermal energy comparable to the output of a power plant, making commercially viable fusion power available as soon as 2050." The United States and the other ITER members are now constructing ITER with the aim to demonstrate that magnetically confined plasmas can produce more fusion power than the power needed to sustain the plasma. This is a critical step towards producing and delivering electricity from fusion energy. Since the international establishment of the ITER project, ITER's construction schedule has slipped and ITER's costs have increased significantly, leading to questions about whether the United States should continue its commitment to participate in ITER. This study will advise how to best advance the fusion energy sciences in the United States given developments in the field, the specific international investments in fusion science and technology, and the priorities for the next ten years developed by the community and the Office of Fusion Energy Sciences (FES) that were recently reported to Congress. It will address the scientific justification and needs for strengthening the foundations for realizing fusion energy given a potential choice of U.S. participation or not in the ITER project, and develops future scenarios in either case. This interim report assesses the current status of U.S. fusion research and of the importance of burning plasma research to the development of fusion energy as well as to plasma science and other science and engineering disciplines. The final report will present strategies that incorporate continued progress toward a burning plasma experiment and a focus on innovation.
Author: John David Elder
Publisher:
ISBN: 9780494393710
Category : Aerospace engineering
Languages : en
Pages : 155
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Book Description
In 2003 and 2005 13CH4 puffing experiments were conducted on DIII-D [1] in L and ELMy H mode plasmas respectively. The motivation for these experiments was to develop a greater understanding of impurity creation, transport and deposition for hydrocarbons which are produced at the walls of DIII-D by chemical sputtering. In both experiments, tiles from around the vessel were removed after the experiment was complete and the distribution of the 13C deposition was measured using nuclear reaction analysis. During each of these experiments the plasma conditions and emissions were monitored by a number of direct and spectroscopic diagnostics including Langmuir probes, Thomson scattering, the multichord divertor spectrometer, filterscopes, reciprocating probes and others. These diagnostic measurements are used in the thesis to develop a background plasma solution for the experiments through the procedure of empirical plasma reconstruction. These background plasma solutions are used as the basis for modeling the emissions, transport and deposition of the 13C resulting from the breakup of 13CH4 using the OEDGE code. OEDGE was enhanced by the addition of improved methane breakup kinetics models, improved peripheral particle transport, improved support for line profile modeling as well as many other features. The modeling successfully reproduces most of the spectroscopic measurements as well as the observed 13C deposition patterns in both distribution and magnitude. In order to match the experimental results, fast parallel transport in the SOL had to be imposed on the carbon ions. In addition, a radial pinch was required in the SOL for both the L and H mode experiments to move the carbon closer to the separatrix so that it could deposit where it was measured experimentally. Without both of these flows the simulations were unable to replicate the experimental observations. The effects of radial variation in the parallel flow and erosion of deposited 13C were also both investigated. It was found that neither of these processes by itself appears to be capable of replicating the experimental results.
Author: John Wesson
Publisher: Oxford University Press
ISBN: 0199592233
Category : Science
Languages : en
Pages : 828
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Book Description
The tokamak is the principal tool in controlled fusion research. This book acts as an introduction to the subject and a basic reference for theory, definitions, equations, and experimental results. The fourth edition has been completely revised, describing their development of tokamaks to the point of producing significant fusion power.
