Organizational Unit:

Fusion Research Center

Permanent Link

https://hdl.handle.net/1853/70733

Parent Organization

Organizational Unit

George W. Woodruff School of Mechanical Engineering

ArchiveSpace Name Record

https://finding-aids.library.gatech.edu/agents/corporate_entities/1150

Full item page

Publication Search Results

Now showing 1 - 10 of 12

Interpretation of particle pinches and diffusion coefficients in the edge pedestal of DIII-D H-mode plasmas

(Georgia Institute of Technology, 2009-10-15) Stacey, Weston M. ; Groebner, Rich J.

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 interpretation of two DIII-D [ J. Luxon, Nucl. Fusion 42, 614 (2002) ]. discharges yields new information about particle pinches and particle diffusion coefficient profiles in the edge pedestal.
Interpretation of edge pedestal rotation measurements in DIII-D

(Georgia Institute of Technology, 2008-01-25) Stacey, Weston M. ; Groebner, Rich J.

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 in the DIII-D J. Luxon, Nucl. Fusion 42, 6149 2002 edge pedestal. The experimentally inferred values have been compared with predictions based on atomic physics processes and on neoclassical toroidal viscosity. The poloidal rotation velocities have been calculated from poloidal momentum balance using neoclassical parallel viscosity and a novel retention of all terms in the poloidal momentum balance, and compared with measured values in the DIII-D edge pedestal.
Edge Pedestal Structure and Transport Interpretation in DIII-D (In the absence of or in between ELMs)

(Georgia Institute of Technology, 2008) Stacey, Weston M. ; Groebner, Rich J.
Implementation of the GTNEUT 2D Neutrals Transport Code for Routine DIII-D Analyses

(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.
Experimentally inferred thermal diffusivities in the edge pedestal between edge-localized modes in DIII-D

(Georgia Institute of Technology, 2007-12-11) Stacey, Weston M. ; Groebner, Rich J.

Using temperature and density profiles averaged over the same subinterval of several successive inter-edge-localized-mode (ELM) periods, the ion and electron thermal diffusivities in the edge pedestal were inferred between ELMs for two DIII-D [ J. Luxon, Nucl. Fusion 42, 614 (2002) ] discharges. The inference procedure took into account the effects of plasma reheating and density buildup between ELMs, radiation and atomic physics cooling, neutral beam heating and ion-electron equilibration, and recycling neutral and beam ionization particle sources in determining the conductive heat flux profiles used to infer the thermal diffusivities in the edge pedestal. Comparison of the inferred thermal diffusivities with theoretical formulas based on various transport mechanisms was inconclusive insofar as identifying likely transport mechanisms.
Thermal transport analysis of the edge region in the low and high confinement stages of a DIII-D discharge

(Georgia Institute of Technology, 2007-01-04) Stacey, Weston M. ; Groebner, Rich J.

The ion and electron thermal diffusivities have been inferred from measured density and temperature profiles in the edge of a DIII-D [ J. Luxon, Nucl. Fusion 42, 614 (2002) ] discharge with a low confinement (L-mode) stage followed by a high confinement (H-mode) stage free of edge localized modes. Conductive heat flux profiles used to construct the inferred thermal diffusivities were calculated taking into account heat convection, radiation, atomic physics effects of recycling neutrals, ion-electron equilibration, and neutral beam heating. The inferred thermal diffusivities were compared with theoretical predictions.
Annual Report 2007 Georgia Tech Fusion Research Center

(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.
Thermal Transport in the DIII-D Edge Pedestal

(Georgia Institute of Technology, 2006) Stacey, Weston M. ; Groebner, Rich J.

A new procedure for inferring χ[subscript i,e] in the plasma edge from experimental data and integrated modeling code calculations has been developed which takes into account atomic physics and radiation effects and convective as well as conductive heat flux profiles. Application to DIII-D shots indicates that the sharp temperature gradient pedestal region may be caused as much, if not more, by an increase (with radius) of the conductive heat flux as by a decrease of the thermal transport coefficient. Inferred χ[subscript i,e][superscript exp] are compared with theoretical predictions.
Investigation of edge pedestal structure in DIII-D (DoE Grant ER54538)

(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.
Application of a particle, momentum and energy balance model to calculate the structure of the edge pedestal in DIII-D

(Georgia Institute of Technology, 2005-04) Stacey, Weston M. ; Groebner, Rich J.

A calculation of edge density and temperature profiles based on "classical" physics - particle, momentum and energy balance, heat conduction closure relations, neutral particle transport - yielded a pedestal structure that is qualitatively and quantitatively similar to that found experimentally in five DIII-D [J. Luxon, Nucl. Fusion,42, 614 (2002)] discharges, when experimental radial electric field and rotation profiles and experimentally inferred heat transport coefficients were used. The principal cause of the density pedestal was a peaking of the inward pinch velocity just inside the separatrix caused by the negative well in the experimental electric field, and the secondary cause was a peaking of the radial particle flux caused by the ionization of incoming neutrals. There is some evidence that this peaking of the radial particle flux just inside the separatrix may also be responsible in part for the negative electric field in that location.