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Fusion Research Center

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Author: Friis, Zachary Ward ×

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Now showing 1 - 5 of 5
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    Analysis of neutral particle recycling and pedestal fueling in a H-mode DIII-D discharge
    (Georgia Institute of Technology, 2010-02-23) Friis, Zachary Ward ; Stacey, Weston M. ; Leonard, Anthony W. ; Rensink, M. E.
    A detailed analysis of neutral atom recycling and pedestal fueling in a DIII-D _J. Luxon, Nucl. Fusion 42, 614 _2002__ high-confinement mode discharge is presented. Experimental data and two-dimensional _2D_ edge plasma fluid code calculations are employed to provide ion wall recycling and recombination neutral sources and background edge plasma parameters for a 2D edge neutral code calculation of detailed neutral density, ionization, and charge-exchange distributions throughout the edge pedestal, scrape-off layer and surrounding halo region, divertor, and private flux regions. The effectiveness of the different neutral sources for fueling the confined plasma is evaluated
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    A semi-automated procedure for creating geometry and background plasma input files for the GTNEUT 2d neutral particle transport code using the uedge plasma edge code
    (Georgia Institute of Technology, 2009-02) Friis, Zachary Ward
    The GTNEUT code1-3 can provide a computationally economical and accurate calculation of neutral particle transport in the complex 2D geometry to the tokamak divertor, scrapeoff layer and edge regions inside of the separatrix. However, the GTNEUT code requires a geometric input file describing this geometry and a background plasma file describing the plasma density and temperature in the various geometric regions. This report describes semi-automated procedures: i) for using (and extending) the input preparation capability of the UEDGE4-5 code to generate a GTNEUT geometric grid input file from a DIII-D EFIT file and ii) for using the plasma density and temperature distributions calculated with the UEDGE code to generate the background plasma input file for GTNEUT.
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    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.
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    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.
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    Investigation of the cause of the High-to-Low mode confinement transition following MARFE formation in DIII-D (DoE Grant ER54538)
    (Georgia Institute of Technology, 2005-10) Stacey, Weston M. ; Friis, Zachary Ward ; Petrie, Thomas W. ; Leonard, Anthony W.
    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 (2002)] was investigated by comparing a theoretical prediction of the threshold non-radiative power across the separatrix needed to maintain H-mode with an experimental determination of the non-radiative power flowing across the separatrix. It was found that in three shots with continuous gas fueling the increased neutral influx associated with the MARFE formation caused a sharp increase in the predicted threshold non-radiative power crossing the separatrix that was required for the plasma to remain in H-mode to a value comparable to the experimental power crossing the separatrix.