Download or read book The Role of Three dimensional Geometry on Turbulence in Quasi helically Symmetric Stellarators written by Benjamin Faber and published by . This book was released on 2018 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ability to optimize stellarator geometry to reduce transport has led to renewed interest in stellarators for magnetic confinement fusion. In this thesis, turbulence in the Helically Symmetric eXperiment (HSX), a quasi-helically symmetric stellarator, is investigated through application of the gyrokinetic code GENE and the new reduced fluid model PTSM3D. Gyrokinetics provides an efficient formalism for high-fidelity plasma turbulence simulations by averaging out the unimportant fast particle gyromotion. Both GENE and PTSM3D are capable of handling three-dimensional stellarator geometries. The first comprehensive simulations of Trapped Electron Mode turbulence in HSX are presented. HSX geometry introduces a complex landscape of unstable eigenmodes, with strongly ballooning modes, non-symmetric modes, and extended modes all coexisting at the same wavelengths. Nonlinear simulations display several characteristics unique to HSX. At long wavelengths, surprisingly large transport is observed despite the corresponding linear growth rates being small, and is attributed to nonlinear mode interactions. Zonal flows are prominent, however the velocity shear is insufficient to be solely responsible for saturation. These linear and nonlinear features are the consequence of the low global magnetic shear of HSX, which allows modes to extend far along field lines and requires simulation domains spanning multiple poloidal turns to properly resolve. Subdominant modes with extended structures play an important role in nonlinear energy transfer at long wavelengths, removing energy from shorter wavelength modes to both drive long-wavelength transport and dissipate energy through transfer to stable modes. Calculations with PTSM3D of triplet correlation times, used to quantify turbulence saturation, support the gyrokinetic results and show geometry plays a crucial role in turbulence saturation. Energy transfer from unstable modes to stable modes through non-zonal modes is the dominant mechanism in quasi-helically symmetric geometry, while zonal modes catalyze transfer in quasi-axisymmetric geometry. PTSM3D triplet correlation time calculations for HSX configurations with different magnetic hill and well depths accurately reproduce the nonlinear simulation trends, demonstrating the suitability of triplet correlation times as the first nonlinearly-derived metric for turbulence optimization.
Download or read book Geometry Dependence of TEM Turbulence in the HSX Stellarator and Comparison to Nonlinear Gyrokinetic Simulation written by Jason Cedric Smoniewski and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Turbulent transport is responsible for much of the energy and particle losses in present-day fusion plasma experiments, and optimization to reduce turbulence will be a major step towards realizing the benefits of fusion energy. Stellarators, with the flexibility afforded by external coils and three-dimensional geometry, may be able to reduce turbulence through careful shaping of the magnetic field. Such optimization relies on the ability of simulations to accurately predict turbulence in real devices, and validation studies are severely lacking for the stellarator. In this dissertation, the magnetic flexibility of the Helically Symmetric eXperiment (HSX) stellarator is exploited to investigate Trapped Electron Mode (TEM) turbulence in quasi-helically symmetric and degraded-symmetry configurations through experimental measurements and gyrokinetic simulation. This work includes the first comparison of nonlinear simulations in the Quasi-Helically Symmetric (QHS) and Mirror configurations, as well as the first comparison of nonlinear simulations at experimental parameters to experimental measurements. A database of archived HSX plasma discharges has enabled the temperature and density profiles to be matched in QHS and Mirror, showing that thermal transport is larger in the Mirror configuration at the mid-radius. Simulations do not reproduce this difference between geometries, but transport is sensitive to whether turbulence is in a ∇[n]-driven or ∇[T][e]-driven regime. More precise gradient measurements would be required for full validation of this geometry dependence. While linear growth rates are not predictive of overall turbulence, general aspects of experimental transport are captured by nonlinear simulations. In both simulation and experiment, the heat flux and density fluctuation amplitude increase more strongly with the density gradient than the temperature gradient, and the simulated heat flux matches measurements within experimental uncertainties for both configurations. This confirms that ∇[n]-driven TEM turbulence is the dominant driver of anomalous transport in HSX. Zonal flows can be important to TEM turbulence saturation, and are present in all nonlinear simulations of HSX. This work includes the first calculation of the linear collisionless zonal flow damping in quasi-symmetric magnetic geometry. Flux-tube, flux-surface, and full-volume calculations of the zonal flow evolution and residual are compared in the QHS and Mirror configurations, as well as the quasi-axial symmetry of the National Compact Stellarator eXperiment (NCSX). Despite quasi-symmetry, the dynamics of the zonal flow in all three configurations are similar to those in a conventional stellarator. The zonal flow oscillation presents another opportunity for comparison between simulation and experiment, but measurement of the zonal flow is left to future work. This dissertation is only the starting point for a validation study on the HSX stellarator. Significant opportunities exist for updated experimental measurements and a deeper investigation into the nonlinear physics responsible for TEM dynamics.
Download or read book Final Report of the Committee on a Strategic Plan for U S Burning Plasma Research written by National Academies of Sciences, Engineering, and Medicine and published by National Academies Press. This book was released on 2019-05-31 with total page 341 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Targeted Optimization of Quasi Symmetric Stellarators written by and published by . This book was released on 2016 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: The proposed research focuses on targeted areas of plasma physics dedicated to improving the stellarator concept. Research was pursued in the technical areas of edge/divertor physics in 3D configurations, magnetic island physics in stellarators, the role of 3D shaping on microinstabilities and turbulent transport and energetic ion confinement in stellarators.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 704 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chemical Abstracts written by and published by . This book was released on with total page 2762 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Plasma Physics and Fusion Energy written by Jeffrey P. Freidberg and published by Cambridge University Press. This book was released on 2008-07-10 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: There has been an increase in interest worldwide in fusion research over the last decade and a half due to the recognition that a large number of new, environmentally attractive, sustainable energy sources will be needed to meet ever increasing demand for electrical energy. Based on a series of course notes from graduate courses in plasma physics and fusion energy at MIT, the text begins with an overview of world energy needs, current methods of energy generation, and the potential role that fusion may play in the future. It covers energy issues such as the production of fusion power, power balance, the design of a simple fusion reactor and the basic plasma physics issues faced by the developers of fusion power. This book is suitable for graduate students and researchers working in applied physics and nuclear engineering. A large number of problems accumulated over two decades of teaching are included to aid understanding.
Download or read book Physics Briefs written by and published by . This book was released on 1994 with total page 1264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Proceedings of the National Academy of Sciences of the United States of America written by and published by . This book was released on 2000 with total page 1532 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Government Reports Announcements Index written by and published by . This book was released on 1991 with total page 578 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Theory of Fusion Plasmas written by Olivier Sauter and published by American Institute of Physics. This book was released on 2008-12-02 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Joint Varenna-Lausanne International Workshop on Theory of Fusion Plasmas takes place every other year in a place particularly favorable for informal and in depth discussions. Invited and contributed papers present state-of-the art researches in theoretical plasma physics, covering all domains relevant to fusion plasmas. This workshop always allows a fruitful mix of experienced researchers and students, to allow for a better understanding of the key theoretical physics models and applications, such as: Theoretical issues related to burning plasmas; Anomalous Transport (Turbulence, Coherent Structures, Microinstabilities) RF Heating and Current Drive; Macroinstabilities; Plasma-Edge Physics and Divertors; Fast particles instabilities.
Download or read book Plasma Physics Index written by and published by . This book was released on 1982 with total page 732 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1969 with total page 1108 pages. Available in PDF, EPUB and Kindle. Book excerpt: NSA is a comprehensive collection of international nuclear science and technology literature for the period 1948 through 1976, pre-dating the prestigious INIS database, which began in 1970. NSA existed as a printed product (Volumes 1-33) initially, created by DOE's predecessor, the U.S. Atomic Energy Commission (AEC). NSA includes citations to scientific and technical reports from the AEC, the U.S. Energy Research and Development Administration and its contractors, plus other agencies and international organizations, universities, and industrial and research organizations. References to books, conference proceedings, papers, patents, dissertations, engineering drawings, and journal articles from worldwide sources are also included. Abstracts and full text are provided if available.
Download or read book Plasma Physics Reports written by and published by . This book was released on 1997 with total page 576 pages. Available in PDF, EPUB and Kindle. Book excerpt: Publishes papers on plasma physics. The journal covers the following topics: high-temperature plasma physics, connected with the problem of controlled nuclear fusion based on magnetic and inertial confinement; physics of cosmic plasma including magnetosphere plasma, sun and stellar plasma, etc.; gas discharge plasma and plasma generated by laser and particle beams.
Download or read book Ideal MHD written by Jeffrey P. Freidberg and published by Cambridge University Press. This book was released on 2014-06-26 with total page 743 pages. Available in PDF, EPUB and Kindle. Book excerpt: Comprehensive, self-contained, and clearly written, this book describes the macroscopic equilibrium and stability of high temperature plasmas.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1989 with total page 1470 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Plasma Science written by National Academies of Sciences Engineering and Medicine and published by . This book was released on 2021-02-28 with total page 291 pages. Available in PDF, EPUB and Kindle. Book excerpt: Plasma Science and Engineering transforms fundamental scientific research into powerful societal applications, from materials processing and healthcare to forecasting space weather. Plasma Science: Enabling Technology, Sustainability, Security and Exploration discusses the importance of plasma research, identifies important grand challenges for the next decade, and makes recommendations on funding and workforce. This publication will help federal agencies, policymakers, and academic leadership understand the importance of plasma research and make informed decisions about plasma science funding, workforce, and research directions.
