Download or read book Transport Induced by Ion impurity Friction in Strongly Rotating Collisional Tokamak Plasma written by Chi-Tien Hsu and published by . This book was released on 1989 with total page 49 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Ion Transport Theory for a Strongly Rotating Beam Injected Tokamak Plasma written by Gary William Neeley and published by . This book was released on 1987 with total page 634 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Neoclassical Theory of Momentum Transport by Collisional Ions in Strongly rotating Tokamak Plasmas with Unbalanced Neutral Beam Injection written by Weston Monroe Stacey and published by . This book was released on 1990 with total page 40 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 Fusion Technology written by and published by . This book was released on 1993 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Driven Rotation Self Generated Flow and Momentum Transport in Tokamak Plasmas written by John Rice and published by Springer Nature. This book was released on 2022-01-13 with total page 158 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a comprehensive look at the state of the art of externally driven and self-generated rotation as well as momentum transport in tokamak plasmas. In addition to recent developments, the book includes a review of rotation measurement techniques, measurements of directly and indirectly driven rotation, momentum sinks, self-generated flow, and momentum transport. These results are presented alongside summaries of prevailing theory and are compared to predictions, bringing together both experimental and theoretical perspectives for a broad look at the field. Both researchers and graduate students in the field of plasma physics will find this book to be a useful reference. Although there is an emphasis on tokamaks, a number of the concepts are also relevant to other configurations.
Download or read book Orbit Effects on Impurity Transport in a 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: Particle orbits in a rotating tokamak plasma are calculated from the equation of motion in the frame that rotates with the plasma. It is found that heavy particles in a rotating plasma can drift away from magnetic surfaces significantly faster with a higher bounce frequency, resulting in a diffusion coefficient much larger than that for a stationary plasma. Particle orbits near the surface of a rotating tokamak are also analyzed. Orbit effects indicate that more impurities can penetrate into a plasma rotating with counter-beam injection. Particle simulation is carried out with realistic experimental parameters and the results are in qualitative agreement with some experimental observations in the Tokamak Fusion Test Reactor (TFTR). 19 refs., 15 figs.
Download or read book Orbit Effects on Impurity Transport in a Rotating Tokamak Plasma written by K. L. Wong and published by . This book was released on 1988 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Turbulent Transport in Rotating Tokamak Plasmas written by Francis James Casson and published by . This book was released on 2011 with total page 294 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Collision Transport in a Low Collisionality Tokamak Plasma with Strong Rotation written by and published by . This book was released on 2007 with total page 169 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Rotational Energy Flux of Collisional Impurity Ions in Tokamaks with Strong Unbalanced Neutral Beam Injection written by Weston Monroe Stacey and published by . This book was released on 1990 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Rotation and Impurity Transport in a Tokamak Plasma with Directed Neutral Beam Injection written by W. M. Stacey (Jr) and published by . This book was released on 1984 with total page 31 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 0 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 1994 with total page 1264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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.
Download or read book Rotation and Impurity Transport in a Tokamak Plasma with Directed Neutral Beam Injection written by Weston M. Stacey and published by . This book was released on 1984 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt:
