(Georgia Institute of Technology, 2008)
Stacey, Weston M.; Rognlien, Thomas D.; Groebner, Rich J.; Friis, Zachary Ward
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 grid to represent the
plasma edge geometry. The grid generation capability built into the UEDGE code,
which utilizes equilibrium fitting data taken from experiment, is being adapted to produce
geometric grids for the complex 2D geometries in the DIII-D plasma edge. The process
for using experimental measurements supplemented by plasma edge calculations to
provide the required background plasma parameters for the GTNEUT calculation will be
systematized once the geometric grid generation is complete.
(Georgia Institute of Technology, 2007)
Stacey, Weston M.; Friis, Zachary Ward; Lao, L.; Groebner, Rich J.
Contents: A. Interpretation of Edge Pedestal Rotation Measurements in DIII-D -- B. Experimentally Inferred Thermal Diffusivities in the Edge Pedestal Between ELMS in DIII-D -- C. Integrated Core-Pedestal-Divertor-Neutrals Modeling -- D. Ion Particle Transport in the Edge Pedestal -- E. Neutral Transport Analysisof DIII-D Experiments -- F. Sub-Critical Transmutation Reactors with Tokamak Fusion Neutron Sources Based on ITER Physics and Technology.
(Georgia Institute of Technology, 2005-10)
Stacey, Weston M.; Groebner, Rich J.
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 experimental density, temperature, rotation velocities and radial electric field
profiles in the edge of three DIII-D [J. Luxon, Nucl. Fusion, 42, 614 (2002)] high-mode plasmas. The
calculation indicated that the cause of the pedestal structure in the density was a momentum balance
requirement for a steep negative pressure gradient to balance the forces associated with an edge peaking
in the inward pinch velocity (caused by the observed edge peaking in the radial electric field and rotation
velocity profiles) and, to a lesser extent, in the outward radial particle flux (caused by the ionization of
recycling neutrals). Thermal and angular momentum transport coefficients were inferred from
experiment and compared with theoretical predictions, indicating that thermal transport coefficients were
of the magnitude predicted by neoclassical and ion-temperature-gradient theories (ions) and electrontemperature-
gradient theory (electrons), but that neoclassical gyroviscous theory plus atomic physics
effects combined were not sufficient to explain the inferred angular momentum transfer rate throughout
the edge region.