Transport and Dynamics in Toroidal Fusion Systems
Abstract
The study entitled, "Transport and Dynamics in Toroidal Fusion Systems," (TDTFS) applied analytical theory and numerical computation to investigate topics of importance to confining plasma, the fourth state of matter, with magnetic fields. A central focus of the work is how nonthermal components of the ion particle distribution affect the "sawtooth" collective oscillation in the core of the tokamak magnetic configuration. Previous experimental and analytical research had shown and described how the oscillation frequency decreases and amplitude increases, leading to "monster" or "giant" sawteeth, when the nonthermal component is increased by injecting particle beams or by exciting ions with imposed electromagnetic waves. The TDTFS study applied numerical computation to selfconsistently simulate the interaction between macroscopic collective plasma dynamics and the nonthermal particles. The modeling used the NIMROD code [Sovinec, Glasser, Gianakon, et al., J. Comput. Phys. 195, 355 (2004)] with the energetic component represented by simulation particles [Kim, Parker, Sovinec, and the NIMROD Team, Comput. Phys. Commun. 164, 448 (2004)]. The computations found decreasing growth rates for the instability that drives the oscillations, but they were ultimately limited from achieving experimentally relevant parameters due to computational practicalities. Nonetheless, this effort provided valuable lessons for integrated simulation of macroscopic plasma dynamics.more »
 Authors:
 Univ. of Wisconsin, Madison, WI (United States)
 Publication Date:
 Research Org.:
 Univ. of Wisconsin, Madison, WI (United States)
 Sponsoring Org.:
 USDOE Office of Science (SC), Fusion Energy Sciences (FES) (SC24)
 OSTI Identifier:
 1320655
 Report Number(s):
 DOE/ER/54868
TRN: US1700264
 DOE Contract Number:
 FG0206ER54868
 Resource Type:
 Technical Report
 Country of Publication:
 United States
 Language:
 English
 Subject:
 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; MAGNETIC CONFINEMENT; SAWTOOTH OSCILLATIONS; PLASMA DENSITY; PLASMA PRESSURE; PLASMA INSTABILITY; TOKAMAK DEVICES; COMPUTERIZED SIMULATION; CALCULATION METHODS; ION TEMPERATURE; TRANSPORT; MAGNETIC ISLANDS; NUMERICAL ANALYSIS; REVERSEFIELD PINCH; MAGNETIC FIELDS; NONLINEAR PROBLEMS; TEMPERATURE GRADIENTS; AMPLITUDES; DISTRIBUTION; INHIBITION; INTERACTIONS; RELAXATION; DYNAMICS; INSTABILITY GROWTH RATES; STABILIZATION; magnetohydrodynamics; plasma simulation; tokamak
Citation Formats
Sovinec, Carl. Transport and Dynamics in Toroidal Fusion Systems. United States: N. p., 2016.
Web. doi:10.2172/1320655.
Sovinec, Carl. Transport and Dynamics in Toroidal Fusion Systems. United States. doi:10.2172/1320655.
Sovinec, Carl. 2016.
"Transport and Dynamics in Toroidal Fusion Systems". United States.
doi:10.2172/1320655. https://www.osti.gov/servlets/purl/1320655.
@article{osti_1320655,
title = {Transport and Dynamics in Toroidal Fusion Systems},
author = {Sovinec, Carl},
abstractNote = {The study entitled, "Transport and Dynamics in Toroidal Fusion Systems," (TDTFS) applied analytical theory and numerical computation to investigate topics of importance to confining plasma, the fourth state of matter, with magnetic fields. A central focus of the work is how nonthermal components of the ion particle distribution affect the "sawtooth" collective oscillation in the core of the tokamak magnetic configuration. Previous experimental and analytical research had shown and described how the oscillation frequency decreases and amplitude increases, leading to "monster" or "giant" sawteeth, when the nonthermal component is increased by injecting particle beams or by exciting ions with imposed electromagnetic waves. The TDTFS study applied numerical computation to selfconsistently simulate the interaction between macroscopic collective plasma dynamics and the nonthermal particles. The modeling used the NIMROD code [Sovinec, Glasser, Gianakon, et al., J. Comput. Phys. 195, 355 (2004)] with the energetic component represented by simulation particles [Kim, Parker, Sovinec, and the NIMROD Team, Comput. Phys. Commun. 164, 448 (2004)]. The computations found decreasing growth rates for the instability that drives the oscillations, but they were ultimately limited from achieving experimentally relevant parameters due to computational practicalities. Nonetheless, this effort provided valuable lessons for integrated simulation of macroscopic plasma dynamics. It also motivated an investigation of the applicability of fluidbased modeling to the ion temperature gradient instability, leading to the journal publication [Schnack, Cheng, Barnes, and Parker, Phys. Plasmas 20, 062106 (2013)]. Apart from the tokamakspecific topics, the TDTFS study also addressed topics in the basic physics of magnetized plasma and in the dynamics of the reversedfield pinch (RFP) configuration. The basic physics work contributed to a study of twofluid effects on interchange dynamics, where "twofluid" refers to modeling independent dynamics of electron and ion species without full kinetic effects. In collaboration with scientist Ping Zhu, who received separate support, it was found that the ruleofthumb criteria on stabilizing interchange has caveats that depend on the plasma density and temperature profiles. This work was published in [Zhu, Schnack, Ebrahimi, et al., Phys. Rev. Lett. 101, 085005 (2008)]. An investigation of general nonlinear relaxation with fluid models was partially supported by the TDTFS study and led to the publication [Khalzov, Ebrahimi, Schnack, and Mirnov, Phys. Plasmas 19, 012111 (2012)]. Work specific to the RFP included an investigation of interchange at large plasma pressure and support for applications [for example, Scheffel, Schnack, and Mirza, Nucl. Fusion 53, 113007 (2013)] of the DEBS code [Schnack, Barnes, Mikic, Harned, and Caramana, J. Comput. Phys. 70, 330 (1987)]. Finally, the principal investigator over most of the award period, Dalton Schnack, supervised a numerical study of modeling magnetic island suppression [Jenkins, Kruger, Hegna, Schnack, and Sovinec, Phys. Plasmas 17, 12502 (2010)].},
doi = {10.2172/1320655},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2016,
month = 9
}

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