Date of Graduation


Document Type


Degree Type



Eberly College of Arts and Sciences


Physics and Astronomy

Committee Chair

Mark Koepke

Committee Member

Paul Cassak

Committee Member

Paul Miller


The application of bicoherence analysis to plasma research, particularly in non-linear, coupled-wave regimes, has thus far been significantly belied by poor resolution in time, and/or outright destruction of frequency information. Though the typical power spectrum cloaks the phase-coherency between frequencies, Fourier transforms of higher-order convolutions provide an n-dimensional spectrum which is adept at elucidating n-wave phase coherence. As such, this investigation focuses on the utility of the normalized bispectrum for detection of wave-wave coupling in general, with emphasis on distinct implications within the scope of non-linear plasma physics. Interpretations of bicoherent features are given for time series from "shots" at the DIII-D tokamak facility; the solar wind, as measured by the Cluster-II satellite installation; a van der Pol oscillator; and various audio signals, both recorded and contrived. Evaluations of the bicoherence exhibited by simple harmonic relationships are contrasted with those displaying truly non-linear signatures, and the temporal dynamics of their respective bispectra are assessed. Also considered are the curatives and caveats of cogently condensing these 4-dimensional data.