Download or read book Test of Local Transport Theory and Reduced Wall Impurity Influx with Highly Radiative Plasmas in the Tokamak Fusion Test Reactor written by K. W. Hill and published by . This book was released on 1998 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Bolometers written by Unil Perera and published by BoD – Books on Demand. This book was released on 2012-03-09 with total page 212 pages. Available in PDF, EPUB and Kindle. Book excerpt: Infrared Detectors and technologies are very important for a wide range of applications, not only for Military but also for various civilian applications. Comparatively fast bolometers can provide large quantities of low cost devices opening up a new era in infrared technologies. This book deals with various aspects of bolometer developments. It covers bolometer material aspects, different types of bolometers, performance limitations, applications and future trends. The chapters in this book will be useful for senior researchers as well as beginning graduate students.
Download or read book Experimental Tests of Parallel Impurity Transport Theory in Tokamak Plasmas written by Matthew Logan Reinke and published by . This book was released on 2012 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt: In realistic reactor scenarios, high temperature plasmas will be composed of not only the fusion reactants and products, but also impurities introduced purposefully or unintentionally from plasma facing materials. In tokamaks it is often assumed, sometimes erroneously, that surfaces of constant main ion pressure are also surfaces of constant impurity pressure. Although the same underlying physics determine impurity momentum balance along closed magnetic field lines, the increased mass and charge of high-Z impurities weights terms differently. Their large mass enhances inertial effects like the centrifugal force from toroidal rotation, and( can lead to accumulation of heavy impurities on the outboard side of a flux surface. Their high charge enhances ion-impurity friction and makes impurities sensitive to small poloidal variations in the electrostatic potential. In Alcator C-Mod, 2D (R,Z) measurements of photon emission from high-Z impurities reveal significant variations of impurity density on a flux surface. Poloidal variations, normalized to the flux surface average, I 2/(n ) , have been measured up to ~ 1/3, and separate cases of impurities accumulating on the inboard and outboard side of a flux surface are observed, depending on local plasmas conditions. Experiments demonstrate that these asymmetries are due to a combination of inertia., poloidal electric fields and ion-impurity friction, and measurements are compared to existing neoclassical parallel impurity transport theory. This is the first time centrifugal force has been observed to cause a substantial asymmetry in a plasma with no external momentum input and where the flow is entirely self-generated. Magnetically trapped fast ions, sustained by ion cyclotron waves, create a poloidally varying electrostatic potential which causes high-Z impurities to accumulate on the inboard side. Existing theory is extended to include this effect by incorporating a species that has an anisotropic pressure tensor. Experimental measurements in plasmas where the minority resonance layer is scanned show good qualitative and quantitative agreement with this extended theory. The sensitivity of 51/(nz) to fast-ions demonstrates the opportunity for the impurity asymmetry to be used as a novel diagnostic tool and calls into question prior work on in/out asymmetries in neutral beam heated plasmas. /down asymmetries in the banana regime are unable to be explained by ion/impurity friction in the trace limit, nZZ 2 /n
Download or read book Theory of Tokamak Transport written by Leslie Colin Woods and published by John Wiley & Sons. This book was released on 2006-05-12 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this new approach for a consistent transport theory in nuclear fusion processes Leslie Woods draws on over 40 years of fusion research to directly compare theoretical findings with experimental results, while taking into account recently discovered phenomena. This is thus the first book to find theoretical explanations to the sometimes-puzzling tokamak observations. Following a look at the quest for fusion power, the author goes on to examine tokamak magnetic fields and energy losses, as well as plasma flow and loop voltage. There is also a discussion of the technical constraints on the recently announced ITER design.
Download or read book Chemical Abstracts written by and published by . This book was released on 2002 with total page 2364 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1991 with total page 1030 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Test Particle Studies of Acceleration and Transport in Solar and Tokamak Plasmas written by Robert McKay and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A test particle approach is used to study two distinct plasma physics situations. In the first case, the collisionless response of protons to cold plasma fast Alfven waves propagating in a non-uniform magnetic field configuration (specifically, a two-dimensional X-point field) is studied. The field perturbations associated with the waves, which are assumed to be azimuthally-symmetric and invariant in the direction orthogonal to the X-point plane, are exact solutions of the linearized ideal magnetohydrodynamic (MHD) equations. The protons are initially Maxwellian, at temperatures that are consistent with the cold plasma approximation. Two kinds of wave solution are invoked: global perturbations, with inward- and outward-propagating components; and purely inward-propagating waves, localised in distance from the X-point null, the wave electric field E having a preferred direction. In both cases the protons are effectively heated in the direction parallel to the magnetic field, although the parallel velocity distribution is generally non-Maxwellian and some protons are accelerated to highly suprathermal energies. This heating and acceleration can be attributed to the fact that protons undergoing E x B drifts due to the presence of the wave are subject to an effective force in the direction parallel to B. The localised wave solution produces more effective proton heating than the global solution, and successive wave pulses have a synergistic effect. This process, which could play a role in both solar coronal heating and late-phase heating in solar flares, is effective for all ion species, but has a negligible direct effect on electrons. However, both electrons and heavy ions would be expected to acquire a temperature similar to that of the protons on collisional timescales. In the second case the same approach is used to study the collisional transport of impurity ions (carbon, mainly, although tungsten ions are also simulated) in spherical tokamak (ST) plasmas with transonic and subsonic toroidal flows. The efficacy of this approach is demonstrated by reproduscing the results of classical transport theory in the large aspect ratio limit. The equilibrium parameters used in the ST modelling are similar to those of plasmas in the MAST experiment. The effects on impurity ion confinement of both counter-current and co-current rotation are determined. Various majority ion density and temperature profiles, approximating measured profiles in rotating and non-rotating MAST plasmas, are used in the modelling. It is shown that transonic rotation (both counter-current and co-current) has the effect of reducing substantially the confinement time of the impurity ions. This effect arises primarily because the impurity ions, displaced by the centrifugal force to the low-field region of the tokamak, are subject to a collisional diffusivity that is greater than the flux surface-averaged value of this quantity. for a given set of plasma profiles, the carbon ions are found to be significantly less well-confined in co-rotating plasmas than in counter-rotating plasmas, although the difference in confinement time between co- and counter-rotation lessens as the mass of the impurity increases. In the case of carbon ions the poloidal distribution of losses exhibits a pronounced up/down asymmetry that is consistent with the direction of the net vertical drift of the impurity ions. Increasing the mass of the impurity ion is also found to significantly decrease the confinement time in the rotating cases, though the confinement time for the case of a stationary plasma is increased. Such studies of impurity transport within tokamaks are important because it is desirable to expel impurity ions from the plasma to avoid both dilution of the fuel ions and unacceptable radiation losses from the plasma.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1983 with total page 1368 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Tokamak Impurity Report written by United States. Division of Magnetic Fusion Energy and published by . This book was released on 1977 with total page 156 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fusion Energy Update written by and published by . This book was released on 1983 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Physics Briefs written by and published by . This book was released on 1988 with total page 918 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Testing the rho Scaling of Thermal Transport Models written by and published by . This book was released on 1997 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Theoretical predictions of ion and electron thermal diffusivities are tested by comparing calculated and measured temperatures in low (L) mode plasmas from the Tokamak Fusion Test Reactor [D.J. Grove and D.M. Meade, Nucl. Fusion 25, 1167 (1985)] nondimensional scaling experiments. The DIII-D [J.L. Luxon and L.G. Davis, Fusion Technol. 8, 441 (1985)] L-mode [rho]* scalings, the transport models of Rebut-Lallia-Watkins (RLW), Boucher's modification of RLW, and the Institute for Fusion Studies-Princeton Plasma Physics Laboratory (IFS-PPPL) model for transport due to ion temperature gradient modes are tested. The predictions use the measured densities in order to include the effects of density profile shape variations on the transport models. The uncertainties in the measured and predicted temperatures are discussed. The predictions based on the DIII- D scalings are within the measurement uncertainties. All the theoretical models predict a more favorable [rho]* dependence for the ion temperatures than is seen. Preliminary estimates indicate that sheared ow stabilization is important for some discharges, and that inclusion of its effects may bring the predictions of the IFS-PPPL model into agreement with the experiments.
Download or read book Collisional Transport of Trace Impurity Ions and the Role of the Radial Electric Field in Spherical Tokamak Plasmas written by Christopher G. Wrench and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The mitigation and control of impurities, or non-fuel ions, in tokamak plasmas is vital for reducing energy losses and an understanding of impurity transport is required in order to predict the performance of present and future tokamak devices. The development and application of a full orbit, test particle code to the study of the collisional transport of test impurity ions in spherical tokamak plasmas is presented. This code is tested against the standard analytic description of collisional transport in magnetised plasmas and is demonstrated to be particularly suited to the study of the tight aspect ratio of the spherical tokamak design. The principle results of the present work concern the investigation of the role of the radial electric field, a feature of high performance tokamak plasmas, on collisional ion transport. It is found that a static radial electric field leads to a significant reduction in the radial transport of test impurity ions. This effect may be explained in terms of a novel radial drift of the test ions arising due to the introduction of collisional Langevin terms to the full orbit, test particle equations of motion. This has significant implications for the confinement of impurity ions in high performance, steady state tokamak discharges. A scaling of this modification with impurity particle mass and charge numbers is derived analytically and verified numerically and a scaling with electric field parameters is derived numerically. A time dependent radial electric field, which models a number of transient events in tokamak plasmas such as the low- to high-mode transition and edge localised modes, is also investigated and attempts at a preliminary comparison between experimental and numerical observations of impurity transport in spherical tokamak devices is presented.
Download or read book INIS Atomindeks written by and published by . This book was released on 1987 with total page 1150 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Plasma Physics Index written by and published by . This book was released on 1982 with total page 936 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 1988 with total page 1132 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Localized Measurements of High frequency Ion Temperature Fluctuations in the Tokamak Fusion Test Reactor written by Harold T. Evensen and published by . This book was released on 1996 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt:
