The Role of Periodic Nonlinear Phenomena (PNP) in Low-Temperature Plasma (LTP) Science*

   Basic elements (e.g., equivalent inductance and equivalent capacitance) of distributed-parameter and lumped-parameter characteristics are inherent to a description of PNP behavior in LTP which is approached, here, 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, experimental examples, and coupled first-order systems fall within this PNP scope.

   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.

   Modulation of wave-mode dynamics in neon glow-discharge plasma wherein a natural spatiotemporal oscillator (pneon-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

   The stimulated emissions of the auroral ionosphere during high-frequency (HF) heating experiments establish the ionosphere as an active medium for wave generation. HF heating experiments exhibit asymmetrically enhanced spectral broadening and driven-oscillator behavior in the incoherent-scatter-radar spectrum. These dynamics resemble the asymmetric spectral broadening of modulated ion-cyclotron waves in the laboratory. In both cases, externally imposed periodic variations in the field-aligned current drawn through the magnetized plasma result, thus establishing a relevance to modulated electrojet experiments.

Seminal contributions from H. Lashinsky (deceased) and collaborative contributions from R. Majeski, D. Hartley, K.D. Weltmann, P. Miller, T. Klinger, N. Brenning, A. Dinklage, and Y. Raitses are gratefully acknowledged..