Download or read book Investigation of Electron Gyro scale Fluctuations in the National Spherical Torus Experiment written by David Ryan Smith and published by . This book was released on 2009 with total page 236 pages. Available in PDF, EPUB and Kindle. Book excerpt: Anomalous electron thermal transport in magnetically-confined plasma hinders efforts to achieve feasible magnetic fusion energy, and an adequate understanding of anomalous electron thermal transport remains elusive. Gyrokinetic simulations of plasma turbulence indicate electron temperature gradient (ETG) turbulence may generate experimentally-relevant electron thermal transport. To investigate ETG turbulence, a collective scattering system was installed on the National Spherical Torus Experiment (NSTX). Collective scattering provides fluctuation measurements with spatial and k-space localization, and the NSTX collective scattering system measures fluctuations on the electron gyro-scale. This Dissertation describes the design and operation of the NSTX collective scattering system and presents fluctuation measurements, gyrokinetic calculations, and transport calculations pertaining to ETG turbulence. Measurements and analysis indicate electron gyro-scale fluctuations are present in a variety of NSTX plasma regimes, and the observed fluctuations are consistent with ETG turbulence. Additional results pertain to the ETG critical gradient, flow shear suppression of ETG turbulence, ETG-driven electron thermal transport, fluctuation magnitudes, and k-spectra. The measurements can be a challenging validation test for nonlinear gyrokinetic simulations.
Download or read book Electron Gyro scale Fluctuation Measurements in National Spherical Torus Experiment H mode Plasmas written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A collective scattering system has measured electron gyro-scale fluctuations in National Spherical Torus Experiment (NSTX) H-mode plasmas to investigate electron temperature gradient (ETG) turbulence. Observations and results pertaining to fluctuation measurements in ETGstable regimes, the toroidal field scaling of fluctuation amplitudes, the relation between between fluctuation amplitudes and transport quantities, and fluctuation magnitudes and k-spectra are presented. Collectively, the measurements provide insight and guidance for understanding ETG turbulence and anomalous electron thermal transport.
Download or read book Study of Turbulent Fluctuations Driven by the Electron Temperature Gradient in the National Spherical Torus Experiment written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Plasma Scattering of Electromagnetic Radiation written by John Sheffield and published by Academic Press. This book was released on 2010-11-25 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt: This work presents one of the most powerful methods of plasma diagnosis in exquisite detail, to guide researchers in the theory and measurement techniques of light scattering in plasmas. Light scattering in plasmas is essential in the research and development of fusion energy, environmental solutions, and electronics. Referred to as the "Bible" by researchers, the work encompasses fusion and industrial applications essential in plasma research. It is the only comprehensive resource specific to the plasma scattering technique. It provides a wide-range of experimental examples and discussion of their principles with worked examples to assist researchers in applying the theory. Computing techniques for solving basic equations helps researchers compare data to the actual experiment New material on advances on the experimental side, such as the application of high density plasmas of inertial fusion Worked out examples of the scattering technique for easier comprehension of theory
Download or read book Overview of Results from the National Spherical Torus Experiment NSTX written by and published by . This book was released on 2009 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt: The mission of NSTX is the demonstration of the physics basis required to extrapolate to the next steps for the spherical torus (ST), such as a plasma facing component test facility (NHTX) or an ST based component test facility (ST-CTF), and to support ITER. Key issues for the ST are transport, and steady state high [beta] operation. To better understand electron transport, a new high-k scattering diagnostic was used extensively to investigate electron gyro-scale fluctuations with varying electron temperature gradient scale-length. Results from n = 3 braking studies confirm the flow shear dependence of ion transport. New results from electron Bernstein wave emission measurements from plasmas with lithium wall coating applied indicate transmission efficiencies near 70% in H-mode as a result of reduced collisionality. Improved coupling of High Harmonic Fast-Waves has been achieved by reducing the edge density relative to the critical density for surface wave coupling. In order to achieve high bootstrap fraction, future ST designs envision running at very high elongation. Plasmas have been maintained on NSTX at very low internal inductance l{sub i} H"0.4 with strong shaping ([kappa] H"2.7, [delta] H"0.8) with [beta]{sub N} approaching the with-wall beta limit for several energy confinement times. By operating at lower collisionality in this regime, NSTX has achieved record non-inductive current drive fraction f{sub NI} H"71%. Instabilities driven by super-Alfvenic ions are an important issue for all burning plasmas, including ITER. Fast ions from NBI on NSTX are super-Alfvenic. Linear TAE thresholds and appreciable fast-ion loss during multi-mode bursts are measured and these results are compared to theory. RWM/RFA feedback combined with n = 3 error field control was used on NSTX to maintain plasma rotation with [beta] above the no-wall limit. The impact of n> 1 error fields on stability is a important result for ITER. Other highlights are: results of lithium coating experiments, momentum confinement studies, scrape-off layer width scaling, demonstration of divertor heat load mitigation in strongly shaped plasmas, and coupling of CHI plasmas to OH ramp-up. These results advance the ST towards next step fusion energy devices such as NHTX and ST-CTF.
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 Issues in Applied Analytical and Imaging Sciences Research 2013 Edition written by and published by ScholarlyEditions. This book was released on 2013-05-01 with total page 1217 pages. Available in PDF, EPUB and Kindle. Book excerpt: Issues in Applied, Analytical, and Imaging Sciences Research: 2013 Edition is a ScholarlyEditions™ book that delivers timely, authoritative, and comprehensive information about Applied Analysis. The editors have built Issues in Applied, Analytical, and Imaging Sciences Research: 2013 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Applied Analysis in this book 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: 2013 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 Recent Physics Results from NSTX written by R. E. Bell and published by . This book was released on 2006 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: The National Spherical Torus Experiment (NSTX) has made considerable progress in advancing the scientific understanding of high performance long-pulse plasmas needed for ITER and future low-aspect-ratio Spherical Torus (ST) devices. Plasma durations up to 1.6s (5 current redistribution times) have been achieved at plasma currents of 0.7 MA with non-inductive current fractions above 65% while achieving {beta}{sub T} and {beta}{sub N} values of 16% and 5.7 (%mT/MA), respectively. Newly available Motional Stark Effect data has allowed systematic study and validation of current drive sources and improved the understanding of ''hybrid''-like scenarios. In MHD research, six mid-plane ex-vessel radial field coils have been utilized to infer and correct intrinsic error fields, provide rotation control, and actively stabilize the n=1 resistive wall mode at ITER-relevant low plasma rotation values. In transport and turbulence, the low aspect ratio and wide range of achievable {beta} in NSTX provide unique data for confinement scaling studies. A new high-k scattering diagnostic is investigating turbulent density fluctuations with wavenumbers extending from ion to electron gyro-scales. In the area of energetic particle research, cyclic neutron rate drops have been associated with the destabilization of multiple large Toroidal Alfven Eigenmodes (TAEs) similar to the ''sea-of-TAE'' modes predicted for ITER. Three wave coupling processes between energetic particle modes and TAEs have also been observed for the first time. In boundary physics, advanced shape control has been utilized to study the role of magnetic balance in H-mode access and ELM stability. Peak divertor heat flux has been reduced by a factor of 5 using an H-mode compatible radiative divertor, and Lithium conditioning has demonstrated particle pumping and improved thermal confinement. Finally, non-solenoidal plasma start-up research is particularly important for the ST, and Coaxial Helicity Injection has now produced 160kA plasma currents on closed magnetic flux surfaces.
Download or read book The National Spherical Torus Experiment NSTX Research Program and Progress Towards High Beta Long PulseOperating Scenarios written by E. J. Synakowski and published by . This book was released on 2002 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Operational Limits in the National Spherical Torus Experiment written by S. M. Kaye and published by . This book was released on 2000 with total page 4 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The National Spherical Torus Experiment NSTX Research Programme and Progress Towards High Beta Long Pulse Operating Scenarios written by and published by . This book was released on 2004 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The National Spherical Torus Experiment NSTX Research Program and Progress Towards High Beta Long PulseOperating Scenarios written by E. J. Synakowski and published by . This book was released on 2002 with total page 12 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Annual Highlights written by Princeton University. Plasma Physics Laboratory and published by . This book was released on 2006 with total page 182 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Progress Towards High Performance Steady state Spherical Torus written by Masayuki Ono and published by . This book was released on 2003 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Validation of Ion and Electron Scale Gyrokinetic Simulations in an NSTX H mode and Comparisons with a Synthetic Diagnostic for High k Scattering written by Juan Ruiz Ruiz (Ph. D.) and published by . This book was released on 2019 with total page 311 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis I perform an extensive validation study in an NSTX NBI-heated H-mode discharge, predicting that electron thermal transport can be entirely explained by shortwavelength electron-scale turbulence fluctuations driven by the electron temperature gradient mode (ETG), both in conditions of strong and weak ETG turbulence drive. For the first time, local, nonlinear gyrokinetic simulation carried out with the GYRO code [98] reproduce the experimental levels of electron thermal transport, the frequency spectrum of electron-scale turbulence, the shape of the wavenumber spectrum and the ratio of fluctuation levels between strongly driven and weakly driven ETG turbulence conditions. Ion thermal transport is very close to neoclassical levels predicted by NEO [215], consistent with stable ion-scale turbulence predicted by GYRO. Quantitative comparisons between high-k fluctuation measurements [65] and simulations are enabled via a novel synthetic high-k diagnostic implemented for GYRO in real-space. A new type of simulation resolving the full ETG spectrum in an unusually large domain (L[subscript r], L[subscript theta]) ~ (20, 20)[subscript rho subscript s] is required to quantitatively compare with the measured frequency spectra of the high-k density fluctuations. Simulations that best match all experimental observables predict that the measured high-k turbulence is closer to the streamer peak of the density fluctuation spectrum than was previously believed. The frequency spectra characteristics of electron-scale turbulence (spectral peak and width) can be consistently reproduced by the synthetic spectra, but these reveal not to be critical constraints on the simulations. The shape of the high-k wavenumber spectrum and the fluctuation level ratio between the strong and weak ETG conditions can also be simultaneously matched by electron-scale simulations within sensitivity scans about the experimental profile values, and result to be great discriminators of the simulations analyzed. Validation metrics are used to discriminate between simulations, are were able to isolate the effect of safety factor and magnetic shear to match the shape of the measured fluctuation wavenumber spectrum. Together, electron thermal transport comparisons and quantitative agreement of electron-scale turbulence spectra give the strongest experimental evidence to date supporting ETG-driven turbulence fluctuations as the main mechanism driving anomalous electron thermal transport in the outer-core of modest [beta] NSTX NBI-heated H-modes.
Download or read book Operational Regimes of the National Spherical Torus Experiment written by and published by . This book was released on 2002 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics Results from the National Spherical Torus Experiment written by and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
