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Book Poloidal Rotation Density Asymmetries and Momentum Confinement in Tokamak Experiments

Download or read book Poloidal Rotation Density Asymmetries and Momentum Confinement in Tokamak Experiments written by and published by . This book was released on 1992 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt: Poloidal rotation speeds and density asymmetries are calculated for the deuterium and dominant carbon (oxygen) impurity ions in discharges in ASDEX, DIII, ISX-B, JET, and TFTR for which [upsilon][sub [phi]] [approximately] [upsilon][sub th] for the ions. These poloidal rotation speeds and density asymmetries are used to evaluate the neoclassical gyroviscous model for the momentum confinement time. The rather good agreement with experimental momentum confinement times obtained over this wide range of plasma parameters provides a measure of confidence in the calculated density asymmetries and poloidal rotation, as well as arguing for a neoclassical explanation for momentum confinement in tokamaks.

Book Energy Research Abstracts

Download or read book Energy Research Abstracts written by and published by . This book was released on 1994-04 with total page 526 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Scientific and Technical Aerospace Reports

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1984 with total page 1278 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Nonlinear Gyrokinetic Simulations of Intrinsic Rotation in Up down Asymmetric Tokamaks

Download or read book Nonlinear Gyrokinetic Simulations of Intrinsic Rotation in Up down Asymmetric Tokamaks written by Justin Richard Ball and published by . This book was released on 2013 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: Experiments and theory show that tokamak plasmas with strong toroidal rotation and rotation shear can suppress turbulent energy transport as well as allow violation of the Troyon [beta] limit. However, using external neutral beams to inject toroidal momentum, as is done in many current experiments, would require a prohibitive amount of energy in larger, reactor-sized devices. The most promising alternative to achieve significant mean plasma flow that scales to large devices is intrinsic rotation, the rotation that is observed in the absence of external momentum injection. Intrinsic rotation is observed in current experiments, but is generated by effects that are formally small in [pi]* =- [pi]i / a, the ratio of the ion gyroradius to the tokamak minor radius. These effects are insufficient in anticipated reactors because [pi]*, will be significantly smaller. Recent theoretical work concludes that up-down asymmetry in the poloidal crosssection of tokamaks can drive intrinsic rotation to lowest order in [pi]*, [1, 2]. In this thesis, we extend GS2, a local [delta] f gyrokinetic code that self-consistently calculates momentum transport, to permit up-down asymmetric configurations. MHD analysis shows that ellipticity is most effective at introducing up-down asymmetry throughout the plasma. Accordingly, tokamaks with tilted elliptical poloidal cross-sections were simulated in GS2 to determine nonlinear momentum transport. The results suggest that the current experimentally measured rotation levels can be generated in reactorsized devices using up-down asymmetry. Surprisingly, linear and nonlinear gyrokinetic simulations also suggest that tilted elliptical flux surfaces may naturally suppress turbulent energy transport. Using cyclone base case parameters [3] (except for an elongation K = 2), a 40% reduction in the linear turbulent growth rate was observed by tilting the flux surface [pi]/4 from vertical. However, this reduction of energy transport was not observed when the background temperature gradient was increased by 50%.

Book Physics Briefs

Download or read book Physics Briefs written by and published by . This book was released on 1993 with total page 1058 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Chemical Abstracts

Download or read book Chemical Abstracts written by and published by . This book was released on 1994-03-07 with total page 1668 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Government Reports Announcements Index

Download or read book Government Reports Announcements Index written by and published by . This book was released on 1993 with total page 1258 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Particle and Momentum Confinement in Tokamak Plasmas with Unbalanced Neutral Beam Injection and Strong Rotation

Download or read book Particle and Momentum Confinement in Tokamak Plasmas with Unbalanced Neutral Beam Injection and Strong Rotation written by Muhammad Afzaal Malik and published by . This book was released on 1986 with total page 98 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Book Evolution of Poloidal Variation of Impurity Density and Ambipolar Potential in Rotating Tokamak Plasma

Download or read book Evolution of Poloidal Variation of Impurity Density and Ambipolar Potential in Rotating Tokamak Plasma written by and published by . This book was released on 1988 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We present numerical results of a 1-D (poloidal), time dependent code for the description of ion impurity transport on a given tokamak magnetic surface, in the presence of momentum sources such that, as observed in neutral beam injection experiments, the toroidal rotation velocities be comparable to or larger than the impurity thermal speed. We show that the densities, the velocities and the ambipolar potential reach a quasi steady state characterized by significant poloidal gradients, on a time scale of the order of the collision time, i.e. faster than the radial diffusion scale. To obtain this steady state a phenomenological drag force needs be introduced; we find that a purely classical, gyroviscous force alone is apparently insufficient to obtain a steady state, within the framework of the present model which retains only the zero-th order, in the Larmor radius expansion, ion-impurity friction.

Book Monthly Checklist of State Publications

Download or read book Monthly Checklist of State Publications written by Library of Congress. Exchange and Gift Division and published by . This book was released on 1993 with total page 648 pages. Available in PDF, EPUB and Kindle. Book excerpt: