Now showing items 37-56 of 84

    • HEP Benchmarking Activity 

      Stacey, Weston M. (Georgia Institute of Technology, 2008)
      A group of people are collaborating in the comparison experimental thermal diffusivities inferred from experimental data measured in the edge pedestal of DIII-D H-mode discharges using different codes. I am providing ...
    • Higher Order Approximations of the TEP Method for Neutral Particle Transport in Edge Plasmas 

      Stacey, Weston M.; Zhang, Dingkang; Mandrekas, John (Georgia Institute of TechnologyAmerican Institute of Physics, 2006)
      Higher order approximations, which take into account the effects of angular anisotropy, spatial non-uniformity and energy dependence of the distribution of neutral particles, have been developed and implemented to extend ...
    • Implementation of the GTNEUT 2D Neutrals Transport Code for Routine DIII-D Analyses 

      Stacey, Weston M.; Rognlien, Thomas D.; Groebner, Richard J.; Friis, Zachary Ward (Georgia Institute of Technology, 2008)
      The Georgia Tech Neutral Transport (GTNEUT) code is being implemented to provide a tool for routine analysis of the effects of neutral atoms on edge phenomena in DIII-D. GTNEUT can use an arbitrarily complex two-dimensional ...
    • Improvements in the 2D TEP Neutral Particle Transport Calculation in Edge Plasmas (DoE Grant ER54538) 

      Zhang, Dingkang; Mandrekas, John; Stacey, Weston M. (Georgia Institute of TechnologyWiley-VCH Verlag GmbH and Co. KGaA, 2005-10)
      Extensions of the 2D Transmission and Escape Probability neutral particle transport method in treating the spatial non-uniformity of collision sources and neutral energy effects are presented. These extensions have been ...
    • An interface current balance formulation of neutral atom transport theory in plasmas 

      Stacey, Weston M. (Georgia Institute of TechnologyAmerican Institute of Physics, 1997-01)
      An interface current balance (ICB) method for neutral particle transport is presented and specialized to the calculation of neutral atom transport in background plasmas. A multigroup extension of the ICB methodology is ...
    • Interpretation of edge pedestal rotation measurements in DIII-D 

      Stacey, Weston M.; Groebner, Richard J. (Georgia Institute of TechnologyAmerican Institute of Physics, 2008-01-25)
      A novel methodology for inferring experimental toroidal angular momentum transfer rates from measured toroidal rotation velocities and other measured quantities has been developed and applied to analyze rotation measurements ...
    • Interpretation of particle pinches and diffusion coefficients in the edge pedestal of DIII-D H-mode plasmas 

      Stacey, Weston M.; Groebner, Richard J. (Georgia Institute of TechnologyAmerican Institute of Physics, 2009-10-15)
      A procedure is described for evaluating particle pinches to be used in interpreting particle diffusion coefficients from measured density and temperature profiles in the edge pedestal of tokamak plasmas. Application to the ...
    • Investigation of background edge thermal transport in ELMing and ELM-suppressed H-modes in DIII-D 

      Stacey, Weston M.; Evans, T. E. (Georgia Institute of TechnologyAmerican Institute of Physics, 2006-11-17)
      Thermal diffusivities are inferred in the plasma edge of a matched pair of DIII-D [J. Luxon, Nucl. Fusion 42, 614 (2002)] high confinement mode discharges, one with edge localized modes (ELMs) present and the other with ...
    • Investigation of edge pedestal structure in DIII-D (DoE Grant ER54538) 

      Stacey, Weston M.; Groebner, Richard J. (Georgia Institute of TechnologyAmerican Institute of Physics, 2005-10)
      A calculation based on the requirements of particle, momentum and energy conservation, conductive heat transport and atomic physics resulting from a recycling and fueling neutral influx was employed to investigate the ...
    • An investigation of some effects of drifts and magnetic field direction in the scrape-off layer and divertor of tokamak plasmas 

      Stacey, Weston M. (Georgia Institute of TechnologyAmerican Institute of Physics, 2009-04-03)
      Various effects of particle drifts in the scrape-off layer (SOL) and divertor of tokamaks have been calculated. The predictions are consistent with several experimentally observed phenomena, e.g., the double reversal of ...
    • Investigation of the cause of the High-to-Low mode confinement transition following MARFE formation in DIII-D (DoE Grant ER54538) 

      Stacey, Weston M.; Friis, Zachary Ward; Petrie, Thomas W.; Leonard, Anthony W. (Georgia Institute of TechnologyAmerican Institute of Physics, 2005-10)
      The common observation that the onset of a core MARFE (Multifaceted Asymmetric Radiation From Edge) is followed immediately by a H-L (High-to-Low) confinement mode transition in DIII-D [J. Luxon, Nucl. Fusion, 42, 614 ...
    • Investigation of transport in the DIII-D edge pedestal 

      Stacey, Weston M. (Georgia Institute of TechnologyAmerican Institute of Physics, 2004-04)
      A comparison of various heat conduction theories with data from several DIII-D [Luxon, Nucl. Fusion, 42, 614, 2002] shots indicates: 1) that neoclassical theory is in somewhat better agreement with experiment than is ion ...
    • Momentum confinement in DIII-D shots with impurities 

      Stacey, Weston M.; Murakami, M. (Georgia Institute of TechnologyAmerican Institute of Physics, 2001-07-05)
      A neoclassical momentum transport model, consisting of gyroviscous and convective components, is applied to the analysis of momentum confinement in DIII-D [Luxon, Anderson, Batty et al., Plasma Physics and Controlled Nuclear ...
    • Neoclassical calculation of poloidal rotation and poloidal density asymmetries in tokamaks 

      Stacey, Weston M. (Georgia Institute of TechnologyAmerican Institute of Physics, 2002-09)
      A previous model for the calculation of poloidal velocities and poloidal density asymmetries in the core of a tokamak plasma is refined and extended by the inclusion of terms which are important for the calculation of these ...
    • A neoclassical calculation of toroidal rotation profiles and comparison with DIII-D measurements 

      Stacey, Weston M.; Johnson, R. W.; Mandrekas, John (Georgia Institute of TechnologyAmerican Institute of Physics, 2006)
      Momentum and particle balance and neoclassical viscosity were applied to calculate the radial profile of toroidal rotation velocity in several DIII-D [J. Luxon, Nucl. Fusion, 42, 614 (2002)] discharges in a variety of ...
    • A neoclassical model for toroidal rotation and the radial electric field in the edge pedestal 

      Stacey, Weston M. (Georgia Institute of TechnologyAmerican Institute of Physics, 2004-06)
      A model for the calculation of toroidal rotation velocities and the radial electric field in the edge pedestal of tokamaks is described. The model is based on particle and momentum balance and the use of the neoclassical ...
    • Neoclassical theory for rotation and impurity transport in tokamaks with neutral beam injection 

      Stacey, Weston M. (Georgia Institute of TechnologyAmerican Institute of Physics, 2001-01)
      A self-consistent, first-principles neoclassical theory for rotation and impurity transport in tokamaks is presented. The implications of this theory for impurity transport in a tokamak are illustrated by a model problem ...
    • Next-step option design studies (DOE GRANT ER54350) 

      Stacey, Weston M.; Mandrekas, John (Georgia Institute of Technology, 2003-12)
    • Next-Step Option Physics (Grant ER54350) 

      Stacey, Weston M.; Mandrekas, John; Hoffman, E. A. (Elisha Albright) (Georgia Institute of Technology, 2004-10)
      For more than a decade we have been involved in physics and design analysis of possible nextstep tokamak options, including first ITER, later FIRE and most recently a tokamak neutron source for a near-term transmutation ...
    • Non-Diffusive Transport in the Tokamak Edge Pedestal 

      Stacey, Weston M.; Groebner, Richard J.; Evans, T. E. (Georgia Institute of TechnologyInstitute of Physics, 2012)
      There are (at least) two classical mechanisms for non-diffusive transport in the edge plasma: i) particle “pinch” velocities due to forces such as VxB, and Er; and ii) outward drifts due to ion-orbit loss and X-transport. ...