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Center for Extended Magnetohydrodynamic Modeling Cooperative Agreement

Description: The Center for Extended Magnetohydrodynamic Modeling (CEMM) is developing computer simulation models for predicting the behavior of magnetically confined plasmas. Over the first phase of support from the Department of Energy’s Scientific Discovery through Advanced Computing (SciDAC) initiative, the focus has been on macroscopic dynamics that alter the confinement properties of magnetic field configurations. The ultimate objective is to provide computational capabilities to predict plasma behavi… more
Date: February 15, 2008
Creator: Sovinec, Carl R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Stable Spheromaks with Profile Control

Description: A spheromak equilibrium with zero edge current is shown to be stable to both ideal MHD and tearing modes that normally produce Taylor relaxation in gun-injected spheromaks. This stable equilibrium differs from the stable Taylor state in that the current density j falls to zero at the wall. Estimates indicate that this current profile could be sustained by non-inductive current drive at acceptable power levels. Stability is determined using the NIMROD code for linear stability analysis. Non-line… more
Date: January 29, 2008
Creator: Fowler, T K & Jayakumar, R
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Final Report for "Implimentation and Evaluation of Multigrid Linear Solvers into Extended Magnetohydrodynamic Codes for Petascale Computing"

Description: Extended magnetohydrodynamic (MHD) codes are used to model the large, slow-growing instabilities that are projected to limit the performance of International Thermonuclear Experimental Reactor (ITER). The multiscale nature of the extended MHD equations requires an implicit approach. The current linear solvers needed for the implicit algorithm scale poorly because the resultant matrices are so ill-conditioned. A new solver is needed, especially one that scales to the petascale. The most successf… more
Date: June 19, 2008
Creator: Vadlamani, Srinath; Kruger, Scott & Austin, Travis
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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A Development Path for the Stabilized Spheromak

Description: In Refs. [1] - [3], I suggest a concerted computational effort to study profile control of spheromaks, in anticipation that it is timely to incorporate the q < 1 regime of RFP's and spheromaks into an integrated advanced toroidal confinement program, together with improvements in tokamaks and stellarators now being pursued. For profile control of spheromaks by neutral beam injection, with care to avoid super-Alfvenic beam instability the main issue is excitation of tearing modes that can be … more
Date: July 13, 2007
Creator: Fowler, T K
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Two-Fluid and Resistive Nonlinear Simulations of Tokamak Equilibrium, Stability, and Reconnection

Description: The NIMROD and M3D / M3D-C1 codes now each have both a resistive MHD and a two-fluid (2F) capability including gyroviscosity and Hall terms. We describe: (1) a nonlinear 3D verification test in the resistive MHD regime in which the two codes are in detailed agreement , (2) new studies that illuminate the effect of two-fluid physics on spontaneous rotation in tokamaks, (3) studies of nonlinear reconnection in regimes of relevance to fusion plasmas with peak nonlinear reconnection rates that are … more
Date: September 1, 2008
Creator: Jardin, S.; Sovinec, C.; Breslau, J.; Ferraro, N.; Hudson, S.; King, J. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Comparisons Between Experimental Measurments and Numerical Simulations of Spheromak Formation in SSPX

Description: Data from a recently installed insertable magnetic probe array in the Sustained Spheromak Physics Experiment (SSPX) [E. B. Hooper et al., Nucl. Fusion 39, 863 (1999)] is compared against NIMROD [C. R. Sovinec et al., J. Comp. Phys. 195, 355 (2004)], a full 3D resistive magnetohydrodynamic code that is used to simulate SSPX plasmas. The experiment probe consists of a linear array of chip inductors arranged in clusters that are spaced every 2 cm, and spans the entire machine radius at the flux co… more
Date: March 15, 2006
Creator: Romero-Talam?s, C. A.; Hooper, E. B.; Hill, D. N.; Cohen, B. I.; McLean, H. S.; Wood, R. D. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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NIMROD Resistive Magnetohydrodynamic Simulations of Spheromak Physics

Description: The physics of spheromak plasmas is addressed by time-dependent, three-dimensional, resistive magneto-hydrodynamic simulations with the NIMROD code. Included in some detail are the formation of a spheromak driven electrostatically by a coaxial plasma gun with a flux-conserver geometry and power systems that accurately model the Sustained Spheromak Physics Experiment (SSPX) (R. D. Wood, et al., Nucl. Fusion 45, 1582 (2005)). The controlled decay of the spheromak plasma over several milliseconds … more
Date: December 11, 2007
Creator: Hooper, E. B.; Cohen, B. I.; McLean, H. S.; Wood, R. D.; Romero-Talamas, C. A. & Sovinec, C. R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Final report for Utah State's SciDAC CEMM contribution

Description: This document represents a summary of work carried out at Utah State University in conjunction with the Center for Extended Magnetohyrodynamic Modeling (CEMM). The principal investigator, Dr. Eric Held, was aided in this work by two former graduate students, Drs. John James and Michael Addae-Kagyah, who completed their PhD's while being partially funded by CEMM monies. In addtion, Dr. Jeong-Young Ji, a postdoctoral researcher and Mukta Sharma, a graduate student were supported. The work associa… more
Date: May 13, 2008
Creator: Held, Dr. Eric
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Spheromak formation studies in SSPX

Description: We present results from the Sustained Spheromak Physics Experiment (SSPX) at LLNL, which has been built to study energy confinement in spheromak plasmas sustained for up to 2 ms by coaxial DC helicity injection. Peak toroidal currents as high as 600kA have been obtained in the 1m dia. (0.23m minor radius) device using injection currents between 200-400kA; these currents generate edge poloidal fields in the range of 0.2-0.4T. The internal field and current profiles are inferred from edge field m… more
Date: September 29, 2000
Creator: Hill, D. N.; Bulmer, R. H.; Cohen, B. L.; Hooper, E. B.; LoDestro, L. L.; Mattor, N. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Simulation of Spheromak Evolution and Energy Confinement

Description: Simulation results are presented that illustrate the formation and decay of a spheromak plasma driven by a coaxial electrostatic plasma gun, and that model the energy confinement of the plasma. The physics of magnetic reconnection during spheromak formation is also illuminated. The simulations are performed with the three-dimensional, time-dependent, resistive magnetohydrodynamic NIMROD code. The dimensional, simulation results are compared to data from the SSPX spheromak experiment at the Lawr… more
Date: November 12, 2004
Creator: Cohen, B; Hooper, E; Cohen, R; Hill, D; McLean, H; Wood, R et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Center for Extended Magnetohydrodynamic Modeling (CEMM) University of Utah SAPP 2007 Final Status Report

Description: During the third and final period of this grant, our goal was to refine the algorithmic approaches used to detect and visualize magnetic islands and their corresponding null points within both the NIMROD and M3D data sets. We refined our geometric approach, which gave a greater confidence in the accuracy of the Poincareplots created. The final results are best demonstrated through Figures 2-6 attached to the report. Technical details this work was reported in both the Physics and Visualization … more
Date: December 4, 2007
Creator: Sanderson, Allen R. & Johnson, Christopher R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Validation of Numerical Two-Fluid and Kinetic Plasma Models

Description: This was a four year grant commencing October 1, 2003 and finishing September 30, 2007. The funding was primarily used to support the work of the Principal Investigator, who collaborated with Profs. Scott Parker and John Cary at U. Colorado, and with two students, N. Xiang and J. Cheng also of U. Colorado. The technical accomplishments of this grant can be found in the publications listed in the final Section here. The main accomplishments of the grant work were: (1) Development and implementat… more
Date: March 25, 2011
Creator: Barnes, Daniel
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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A NATIONAL COLLABORATORY TO ADVANCE THE SCIENCE OF HIGH TEMPERATURE PLASMA PHYSICS FOR MAGNETIC FUSION

Description: This report summarizes the work of the University of Utah, which was a member of the National Fusion Collaboratory (NFC) Project funded by the United States Department of Energy (DOE) under the Scientific Discovery through Advanced Computing Program (SciDAC) to develop a persistent infrastructure to enable scientific collaboration for magnetic fusion research. A five year project that was initiated in 2001, it the NFC built on the past collaborative work performed within the U.S. fusion communi… more
Date: August 1, 2006
Creator: Sanderson, Allen R. & Johnson, Christopher R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Magnetic Reconnection in the Spheromak: Physics and Consequences

Description: Magnetic reconnection in the spheromak changes magnetic topology by conversion of injected toroidal flux into poloidal flux and by magnetic surface closure (or opening) in a slowly decaying spheromak. Results from the Sustained Spheromak Physics Experiment, SSPX, are compared with resistive MHD simulations using the NIMROD code. Voltage spikes on the SSPX gun during spheromak formation are interpreted as reconnection across a negative-current layer close to the mean-field x-point. Field lines a… more
Date: February 28, 2006
Creator: Hooper, E. B.; Cohen, B. I.; Hill, D. N.; LoDestro, L. L.; McLean, H. S.; Romero-Talamas, C. A. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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Conversion of NIMROD simulation results for graphical analysis using VisIt

Description: Software routines developed to prepare NIMROD [C. R. Sovinec et al., J. Comp. Phys. 195, 355 (2004)] results for three-dimensional visualization from simulations of the Sustained Spheromak Physics Experiment (SSPX ) [E. B. Hooper et al., Nucl. Fusion 39, 863 (1999)] are presented here. The visualization is done by first converting the NIMROD output to a format known as legacy VTK and then loading it to VisIt, a graphical analysis tool that includes three-dimensional rendering and various mathem… more
Date: May 3, 2006
Creator: Romero-Talamas, C. A.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Numerical Studies of Magnetohydrodynamic Activity Resulting from Inductive Transients Final Report

Description: This report describes results from numerical studies of transients in magnetically confined plasmas. The work has been performed by University of Wisconsin graduate students James Reynolds and Giovanni Cone and by the Principal Investigator through support from contract DE-FG02-02ER54687, a Junior Faculty in Plasma Science award from the DOE Office of Science. Results from the computations have added significantly to our knowledge of magnetized plasma relaxation in the reversed-field pinch (RFP… more
Date: August 29, 2005
Creator: Sovinec, Carl R.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Large experiment data analysis collaboration. Annual progress report for period November 15, 1999 - November 14, 2000

Description: Neoclassical tearing modes have now entered the mainstream of tokamak research. One indication of this was the featuring of it in the ITER MHD instabilities paper at the 1998 Yokohama meeting, of which we (along with many colleagues throughout the world) were co-authors. In addition, this past year a number of talks were given on various aspects of neoclassical tearing modes and their impacts in tokamak plasmas. At present, we are anxiously awaiting the DIII-D electron cyclotron heating and cur… more
Date: July 10, 2000
Creator: Callen, J. D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Modeling of Neoclassical Tearing Mode Stability for Generalized Toroidal Geometry

Description: Neoclassical tearing modes (NTMs) can lead to disruption and loss of confinement. Previous analysis of these modes used large aspect ratio, low beta (plasma pressure/magnetic pressure) approximations to determine the effect of NTMs on tokamak plasmas. A more accurate tool is needed to predict the onset of these instabilities. As a follow-up to recent theoretical work, a code has been written which computes the tearing mode island growth rate for arbitrary tokamak geometry. It calls PEST-3 [A. P… more
Date: August 21, 2002
Creator: Rosenberg, A. L.; Gates, D. A.; Pletzer, A.; Menard, J. E.; Kruger, S. E.; Hegna, C. C. et al.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Nonlinear and Nonideal MHD

Description: The primary efforts this year have focused on exploring the nonlinear evolution of localized interchange instabilities, some extensions of neoclassical tearing mode theory, and developing a model for the dynamic electrical conductivity in a bumpy cylinder magnetic field. In addition, we have vigorously participated in the computationally-focused NIMROD and CEMM projects.
Date: November 4, 2002
Creator: Callen, J. D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Large experiment data analysis collaboration. Final annual progress report for period November 15, 2000 - April 30, 2002

Description: Because of the good agreement between theory and experiment (on a number of tokamak experiments) on the nonlinear development, saturation of neoclassical tearing modes (NTMs), the study of NTMs is becoming a mature subject. Thus, our contributions to studies of neoclassical (and regular classical) tearing modes over the past year have focused on a number of particular, more detailed issues: flow shear effects on linear tearing modes, exploring the possibility of NTMs in spherical tokamaks such … more
Date: January 14, 2002
Creator: Callen, J. D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
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Large experiment data analysis collaboration. Annual progress report for period November 15, 1998 - November 14, 1999

Description: Studies of neoclassical tearing modes have remained the dominant area of research on this grant. This year articles and reports on our previous research projects in collaboration with GA colleagues on a new nonlinear tearing mode model, seed island excitation from geometrically coupled perturbations, the combination of flow shear and viscosity on magnetic islands, and ITER projections got published. A major new theoretical achievement by our group was the development of generalized reduced MHD … more
Date: June 30, 1999
Creator: Callen, J. D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Simulation of Spheromak Evolution and Energy Confinement

Description: Simulation results are presented that illustrate the formation and decay of a spheromak plasma driven by a coaxial electrostatic plasma gun, and that model the energy confinement of the plasma. The physics of magnetic reconnection during spheromak formation is also illuminated. The simulations are performed with the three-dimensional, time-dependent, resistive magnetohydrodynamic NIMROD code. The simulation results are compared to data from the SSPX spheromak experiment at the Lawrence Livermor… more
Date: November 9, 2004
Creator: Cohen, B; Hooper, E; Cohen, R; Hill, D; McLean, H; Wood, R et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
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