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Parametric excitation of kinetic modes

Author: Fred Skiff
Requested Type: Poster Only
Submitted: 2015-01-19 13:03:32

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Contact Info:
University of Iowa
203 Van Allen Hall
Iowa City, IA   52242
USA

Abstract Text:
Recent experiments on phase-space resolved correlation functions show evidence of nonlinear three-wave coupling between unstable electrostatic waves of long wavelength parallel to the magnetic field and linearly damped kinetic modes. Bicoherence estimates are obtained from normalized correlations of the form:
<f(t)f(t-t1)f(t-t2)>. In the frequency domain values close to 0.2 are observed where the density oscillation is near 0.1. A simple theory for a kinetic parametric instability will be presented which may be able to account for the observed nonlinear coupling. This theory can be formulated both from the continuum theory of Case-Van Kampen modes as well (using the G- transform developed by Morrison) or by using the discrete kinetic spectrum which occurs in the weakly collisional case.

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