The Role of Periodic Nonlinear Phenomena (PNP) in Plasma Dynamics*

Basic elements (e.g., equivalent inductance and equivalent capacitance) of distributed-parameter and lumped-parameter characteristics are inherent to a description of PNP behavior which, here, is approached from theory and experiment perspectives. The basic, physical, and mathematical descriptions of PNP, respective prototype PNP systems, and PNP’s connection to turbulence will be outlined. Amplitude-frequency-phase relations and harmonic generation, and coupled first-order systems fall within this PNP scope. Experimental examples are plentiful:

(a) Modulation of wave-mode dynamics in neon glow-discharge plasma wherein a natural spatiotemporal oscillator (p neon-ionization wave) interacts with a spatiotemporal driving force (ionization wave locked to chopped neon-resonant laser light) exhibits the key effect of mode-amplitude normalization of the driving force term in the periodic-pulling equations

(b) The stimulated emissions of the auroral ionosphere during high-frequency heating experiments exhibit PNP-category driven-oscillator behavior in the incoherent-scatter-radar spectrum.

(c) optogalvanic spectroscopy can be achieved using PNP methods.

(d) PNP signatures of entrainment, frequency and wavenumber pulling, excitation thresholds, and particle transport have been observed in plasma thrusters where spatiotemporal “spokes” modulate the breathing oscillations in E×B plasma discharges.

Contributions from H. Lashinsky, R. Majeski, D. Hartley, K.D. Weltmann, P. Miller, T. Klinger, N. Brenning, A. Dinklage, and Y. Raitses are gratefully acknowledged.