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Title: A theory-based transport model with comprehensive physics

Abstract

A new theory-based transport model with comprehensive physics (trapping, general toroidal geometry, fully electromagnetic, electron-ion collisions, impurity ions) has been developed. The core of the model is the new trapped-gyro-Landau-fluid (TGLF) equations, which provide a fast and accurate approximation to the linear eigenmodes for gyrokinetic drift-wave instabilities (trapped ion and electron modes, ion and electron temperature gradient modes, and kinetic ballooning modes). The new TGLF transport model is more accurate, and has an extended range of validity, compared to its predecessor GLF23. The TGLF model unifies trapped and passing particles in a single set of gyro-Landau-fluid equations. A model for the averaging of the Landau resonance by the trapped particles makes the equations work seamlessly over the whole drift-wave wave-number range from trapped ion modes to electron temperature gradient modes. A fast eigenmode solution method enables unrestricted magnetic geometry. The transport model uses the TGLF eigenmodes to compute quasilinear fluxes of energy and particles. A model for the saturated intensity of the turbulence completes the flux calculation. The intensity model is constructed to fit a large set of nonlinear gyrokinetic turbulence simulations with kinetic electrons. The TGLF model is valid in new physical regimes that GLF23 was not. These includemore » the low aspect ratio spherical torus, which has both a high trapped fraction and strong shaping of magnetic flux surfaces. The TGLF model is also valid close to the magnetic separatrix so the transport physics of the H-mode pedestal region can be explored.« less

Authors:
; ;  [1];  [2];  [2]
  1. General Atomics, P.O. Box 85608, San Diego, California 92186-5608 (United States)
  2. (United States)
Publication Date:
OSTI Identifier:
20975037
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 14; Journal Issue: 5; Other Information: DOI: 10.1063/1.2436852; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; APPROXIMATIONS; ASPECT RATIO; BALLOONING INSTABILITY; DRIFT INSTABILITY; ELECTRON TEMPERATURE; ELECTRON-ION COLLISIONS; ELECTRONS; H-MODE PLASMA CONFINEMENT; IONS; NONLINEAR PROBLEMS; PLASMA; PLASMA FLUID EQUATIONS; PLASMA IMPURITIES; PLASMA SIMULATION; TEMPERATURE GRADIENTS; TOKAMAK DEVICES; TRANSPORT THEORY; TRAPPING; WAVE PROPAGATION

Citation Formats

Staebler, G. M., Kinsey, J. E., Waltz, R. E., Lehigh University, Bethlehem, Pennsylvania 18015, and General Atomics, P.O. Box 85608, San Diego, California 92186-5608. A theory-based transport model with comprehensive physics. United States: N. p., 2007. Web. doi:10.1063/1.2436852.
Staebler, G. M., Kinsey, J. E., Waltz, R. E., Lehigh University, Bethlehem, Pennsylvania 18015, & General Atomics, P.O. Box 85608, San Diego, California 92186-5608. A theory-based transport model with comprehensive physics. United States. doi:10.1063/1.2436852.
Staebler, G. M., Kinsey, J. E., Waltz, R. E., Lehigh University, Bethlehem, Pennsylvania 18015, and General Atomics, P.O. Box 85608, San Diego, California 92186-5608. Tue . "A theory-based transport model with comprehensive physics". United States. doi:10.1063/1.2436852.
@article{osti_20975037,
title = {A theory-based transport model with comprehensive physics},
author = {Staebler, G. M. and Kinsey, J. E. and Waltz, R. E. and Lehigh University, Bethlehem, Pennsylvania 18015 and General Atomics, P.O. Box 85608, San Diego, California 92186-5608},
abstractNote = {A new theory-based transport model with comprehensive physics (trapping, general toroidal geometry, fully electromagnetic, electron-ion collisions, impurity ions) has been developed. The core of the model is the new trapped-gyro-Landau-fluid (TGLF) equations, which provide a fast and accurate approximation to the linear eigenmodes for gyrokinetic drift-wave instabilities (trapped ion and electron modes, ion and electron temperature gradient modes, and kinetic ballooning modes). The new TGLF transport model is more accurate, and has an extended range of validity, compared to its predecessor GLF23. The TGLF model unifies trapped and passing particles in a single set of gyro-Landau-fluid equations. A model for the averaging of the Landau resonance by the trapped particles makes the equations work seamlessly over the whole drift-wave wave-number range from trapped ion modes to electron temperature gradient modes. A fast eigenmode solution method enables unrestricted magnetic geometry. The transport model uses the TGLF eigenmodes to compute quasilinear fluxes of energy and particles. A model for the saturated intensity of the turbulence completes the flux calculation. The intensity model is constructed to fit a large set of nonlinear gyrokinetic turbulence simulations with kinetic electrons. The TGLF model is valid in new physical regimes that GLF23 was not. These include the low aspect ratio spherical torus, which has both a high trapped fraction and strong shaping of magnetic flux surfaces. The TGLF model is also valid close to the magnetic separatrix so the transport physics of the H-mode pedestal region can be explored.},
doi = {10.1063/1.2436852},
journal = {Physics of Plasmas},
number = 5,
volume = 14,
place = {United States},
year = {Tue May 15 00:00:00 EDT 2007},
month = {Tue May 15 00:00:00 EDT 2007}
}
  • Predictive transport and current drive simulations are presented for the time evolution of the temperature and density profiles in the Tokamak Physics Experiment (TPX). [W. M. Nevins {ital et} {ital al}., {ital Proceedings} {ital of} {ital the} {ital International} {ital Conference} {ital on} {ital Plasma} {ital Physics} {ital and} {ital Controlled} {ital Nuclear} {ital Fusion} {ital Research}, W{umlt u}rzburg, 1992 (International Atomic Energy Agency, Vienna, 1992), Vol. 3, p. 279]. A distinguishing feature of this study is that we use a theoretically derived transport model that has been empirically calibrated against Ohmic, low-confinement and high-confinement mode discharges from seven differentmore » tokamaks. Heating and deposition profiles predicted by the ACCOME current drive and magnetohydrodynamic equilibrium code [R. S. Devoto {ital et} {ital al}., Nucl. Fusion {bold 32}, 773 (1992)] are incorporated into the time-dependent BALDUR one-and-one-half dimensional transport code [C. E. Singer {ital et} {ital al}., Comput. Phys. Commun. {bold 49}, 275 (1988)]. We consider various scenarios of fast wave, lower hybrid, and neutral beam heating and current drive and evaluate the effects on the evolution of density and temperature profiles. {copyright} {ital 1996 American Institute of Physics.}« less
  • A random-matrix model is used to describe the transformation of kinetic energy of relative motion into intrinsic excitation energy typical of a deeply inelastic heavy-ion collision. The random-matrix model is based upon statistical assumptions regarding the form factors coupling relative motion with intrinsic excitation of either fragment. Average cross sections are calculated by means of an ensemble average over the random matrix model. Summations over intermediate and final intrinsic spin values are performed. As a result, average cross sections are given by the asymptotic behavior of a probability density which in turn obeys a transport equation. In the transport equationmore » there is no further reference to intrinsic spins. The physical and mathematical properties of this equation are exhibited.« less
  • Typical features of the transport equation derived in a previous paper are studied in the frame of a one-dimensional model. The optical-model Green's function is constructed, and the mean free path is evaluated numerically. The domain of validity of the semiclassical approximation to the transport equation is evaluated, the significance of conserving approximations is pointed out. For strong absorption (short mean free path) it is shown that quantum fluctuations caused by the uncertainty principle are important. Approximation methods are introduced and tested numerically.
  • A theoretical model of flux-surface-averaged radial transport in tokamaks has been tested and re-calibrated against a well-documented set of temperature and density profiles from a pre-defined set of discharges from six tokamaks. The transport theory includes neoclassical, drift/[eta][sub [ital i]], circulating electron mode, kinetic ballooning, neoclassical magnetohydrodynamic (MHD), and resistive ballooning effects. Allowing for no explicitly adjustable free parameters and no [ital a] [ital posteriori] exclusion of data subsets, the nominal theory reproduced observed temperatures and electron densities with relative error about two orders of magnitude smaller than the range over which machine parameters and resulting plasma parameters varied inmore » the reference discharges examined. An important feature of this study is a well-defined procedure for setting boundary conditions at an appropriate location just inside the inner-most closed'' magnetic flux surface.« less
  • The transport equation deduced previously is cast into a form which allows for numerical computation of cross sections. The approximations, especially the moments approach, are exhibited, as are the essential points of the numerical procedure. The validity of the Einstein relation is discussed. Doubly differential cross sections for various fragments produced in the reaction /sup 40/Ar+/sup 232/Th are calculated and compared with experimental data.