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epr_schaffner_webversion.pdf2014-08-19 20:46:41David Schaffner

MHD Turbulence Analysis of a Relaxing Spheromak in a Plasma Wind Tunnel

Author: David A Schaffner
Requested Type: Consider for Invited
Submitted: 2014-05-30 10:20:02

Co-authors: M.R. Brown, V.S. Lukin, A. Wan

Contact Info:
Swarthmore College
500 College Ave.
Swarthmore, PA   19081
USA

Abstract Text:
Magnetic energy extracted from the transition of an unstable spheromak into a Taylor state drives a turbulent cascade in the wind-tunnel configuration of the Swarthmore Spheromak Experiment (SSX). Magnetic, velocity, and density fluctuations are recorded and reveal turbulent power-law spectra and intermittency. Spectra have indices that tend to be steeper than that predicted by Kolmogorov turbulence theory and are made both temporally and spatially using multi-channeled diagnostics. Comparisons between the resulting frequency and wavenumber are used to probe the validity of the frozen-in flow hypothesis. Variation of the helicity of the injected plasma plume is shown to modify the observed intermittency without affecting the indices of the spectra. Results show favorable statistical comparisons to both a Hall-MHD simulation and to MHD turbulence observations of the solar wind and the magnetosphere.

Characterization: 4.0

Comments:

Workshop on Exploratory Topics in Plasma and Fusion Research (EPR) and US-Japan Compact Torus (CT) Workshop
August 5-8, 2014
Madison, Wisconsin

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