Chaos in reversed-field-pinch plasma simulation and experiment
We investigate the possibility that chaos and simple determinism are governing the dynamics of reversed-field-pinch (RFP) plasmas using data from both numerical simulations and experiment. A large repertoire of nonlinear-analysis techniques is used to identify low-dimensional chaos. These tools include phase portraits and Poincare sections, correlation dimension, the spectrum of Lyapunov exponents, and short-term predictability. In addition, nonlinear-noise-reduction techniques are applied to the experimental data in an attempt to extract any underlying deterministic dynamics. Two model systems are used to simulate the plasma dynamics. These are the DEBS computer code, which models global RFP dynamics, and the dissipative trapped-electron-mode model, which models drift-wave turbulence. Data from both simulations show strong indications of low-dimensional chaos and simple determinism. Experimental data were obtained from the Madison Symmetric Torus RFP and consist of a wide array of both global and local diagnostic signals. None of the signals shows any indication of low-dimensional chaos or other simple determinism. Moreover, most of the analysis tools indicate that the experimental system is very high dimensional with properties similar to noise. Nonlinear noise reduction is unsuccessful at extracting an underlying deterministic system.
- (Department of Physics, University of Wisconsin Madison, Madison, Wisconsin 53706 (United States))
- Publication Date:
- OSTI Identifier:
- Resource Type:
- Journal Article
- Resource Relation:
- Journal Name: Physical Review. E, Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics; (United States); Journal Volume: 49:3
- Country of Publication:
- United States
- 70 PLASMA PHYSICS AND FUSION TECHNOLOGY; PLASMA; REVERSE-FIELD PINCH; COMPUTERIZED SIMULATION; DYNAMICS; NONLINEAR PROBLEMS; PHASE SPACE; TOROIDAL PINCH DEVICES; TURBULENCE; CLOSED PLASMA DEVICES; MATHEMATICAL SPACE; MECHANICS; PINCH DEVICES; PINCH EFFECT; SIMULATION; SPACE; THERMONUCLEAR DEVICES 700330* -- Plasma Kinetics, Transport, & Impurities-- (1992-); 700340 -- Plasma Waves, Oscillations, & Instabilities-- (1992-)
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