Abstract Details
Abstracts
Author: Williams D.V. Sidney
Requested Type: Poster
Submitted: 2025-03-10 15:15:36
Co-authors: Matthew N. Gudorf, Dmitri M. Orlov
Contact Info:
University Of California San Diego
9500 Gilman Dr
La Jolla, CA 92093
United States
Abstract Text:
Turbulence is a key challenge in understanding transport phenomena in magnetically confined plasmas. One method of approaching turbulence is through focusing on the recognizable structures within the complex dynamics. This structural approach is especially prevalent in studies of the scrape-off layer [1], and in dynamical systems analyses of fluid turbulence where periodic orbits are shown to form a ‘skeleton’ for the turbulent motion [2].
In this work, we provide a bridge between nonlinear dynamical systems theory and plasma physics by identifying fundamental structures that underpin turbulent motion. We apply numerical optimization to the Kuramoto-Sivashinsky equation - a reduced model for drift-wave-driven trapped particle turbulence [3] - to extract coherent space-time patterns that serve as building blocks of turbulent dynamics. These structures provide a framework to systematically describe turbulence as a composition of recurrent solutions and behaviors, revealing an underlying order within chaotic plasma motion. This picture of turbulence allows for average physical quantities (in our case: fluctuation intensity, anomalous diffusion coefficient, and flux of turbulent kinetic energy) to be determined with minimal information. Using only the fundamental structures as support, we obtain an approximation which is remarkably accurate when compared to averages taken over long-time integrated solutions.
This success with the Kuramoto-Sivashinsky equation is the first step in developing tools with which to analyze chaotic motion in plasmas through a deterministic, pattern-based lens.
[1] T.A. Carter Phys. Plasmas 13.1 (Jan. 2006).
[2] N.B. Budanur et. al. Journal of Fluid Mechanics 833 (Nov. 2017).
[3] R.E. LaQuey et. al. Physical Review Letters 34.7 (Feb. 1975).
Characterization: 4.0
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