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Published September 2008 | Published
Journal Article Open

Plasma Edge Kinetic-MHD Modeling in Tokamaks Using Kepler Workflow for Code Coupling, Data Management and Visualization

Abstract

A new predictive computer simulation tool targeting the development of the H-mode pedestal at the plasma edge in tokamaks and the triggering and dynamics of edge localized modes (ELMs) is presented in this report. This tool brings together, in a coordinated and effective manner, several first-principles physics simulation codes, stability analysis packages, and data processing and visualization tools. A Kepler workflow is used in order to carry out an edge plasma simulation that loosely couples the kinetic code, XGC0, with an ideal MHD linear stability analysis code, ELITE, and an extended MHD initial value code such as M3D or NIMROD. XGC0 includes the neoclassical ion-electron-neutral dynamics needed to simulate pedestal growth near the separatrix. The Kepler workflow processes the XGC0 simulation results into simple images that can be selected and displayed via the Dashboard, a monitoring tool implemented in AJAX allowing the scientist to track computational resources, examine running and archived jobs, and view key physics data, all within a standard Web browser. The XGC0 simulation is monitored for the conditions needed to trigger an ELM crash by periodically assessing the edge plasma pressure and current density profiles using the ELITE code. If an ELM crash is triggered, the Kepler workflow launches the M3D code on a moderate-size Opteron cluster to simulate the nonlinear ELM crash and to compute the relaxation of plasma profiles after the crash. This process is monitored through periodic outputs of plasma fluid quantities that are automatically visualized with AVS/Express and may be displayed on the Dashboard. Finally, the Kepler workflow archives all data outputs and processed images using HPSS, as well as provenance information about the software and hardware used to create the simulation. The complete process of preparing, executing and monitoring a coupled-code simulation of the edge pressure pedestal buildup and the ELM cycle using the Kepler scientific workflow system is described in this paper.

Additional Information

"First published in Communications in Computational Physics in 4(3), published by Global Science Press." © 2008 Global-Science Press. Received 2 November 2007; Accepted (in revised version) 28 January 2008. Available online 21 April 2008. This work is part of the ongoing research activities within the SciDAC Fusion Simulation Prototype (FSP) Center for Plasma Edge Simulation, which is supported by the Office of Fusion Energy Sciences and the Office of Advanced Scientific Computing Research within the U.S. Department of Energy. We are grateful to the National Center for Computational Science at Oak Ridge National Laboratory and the National Energy Research Supercomputer Center at Lawrence Berkeley National Laboratory for access to and support of their computing resources. Finally, we would like to thank the members of the M3D, ELITE, TEQ, and NIMROD development teams for providing code access and their expertise in utilizing each of these code components effectively. Special Issue on Numerical Simulation of Plasmas, Communications in Computational Physics, 4(3), 2008. http://www.global-sci.com/issue/contents/4/issue3.free.html (Volume 4, issue 3, 2008)

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Created:
August 22, 2023
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October 17, 2023