Spatial relaxation of selective laser perturbations in a glow discharge plasma.

An effect of a nonlocal plasma response caused by local laser radiation exciting atoms in resonant and metastable states is observed in a dc neon glow discharge. Starting at the perturbed position, spatially damped oscillations in the direction of the anode effecting all plasma quantities are created. Depending on the excitation of resonant or metastable atoms, the oscillations are phase-shifted by π. If the laser excites in particular a cycling transition, no nonlocal plasma response is observed. The relaxation of the plasma is investigated by means of visible light measurements using a line camera in the vicinity of the axial perturbation position. The effect is modeled in terms of nonlocal electron kinetics by solving the spatially inhomogeneous electron Boltzmann equation.

Spatiotemporal synchronization of coupled oscillators in a laboratory plasma.

The spatiotemporal synchronization between two plasma instabilities of autonomous glow discharge tubes is observed experimentally. For this purpose, two tubes are placed separately and two chaotic waves interact with each other through a coupler. When the coupling strength is changed, the coupled oscillators exhibit synchronization in time and space. This is the first experimental evidence of spatiotemporal synchronization by mutual chaotic wave interaction in plasma.

Kinetic resonances and stratification of the positive column of a discharge.

Resonance formation of the electron velocity distribution function (EDF) in an inert gas dc discharge at low pressures and small currents is analyzed on the basis of an accurate numerical solution of the Boltzmann kinetic equation in spatially periodic sinusoidally modulated striation-like fields. Calculations are performed for neon at pressures around 1 Torr . The dependences of the EDF, electron density and mean energy, and excitation rate on the electric field spatial period length are investigated. In addition to resonances corresponding to S and P striations predicted by linear analytical theory, the kinetic model indicates the presence of a resonance that can be attributed to an R striation. This resonance is more pronounced at lower pressures when R striations are observed experimentally. The influence of inelastic collisions on the EDF formation in the resonance fields is analyzed.

Resonance effects in the electron distribution function formation in spatially periodic fields in inert gases.

The calculations of the electron distribution function (EDF) in striationlike, sinusoidally modulated electric fields were performed to determine the dependence on spatial period length. The calculations were done for a discharge in neon at pR=2 Torr cm, i/R=5 mA/cm, and electric field E/p=1.9 V cm(-1) Torr(-1). The presence of the resonances in the EDF and macroscopic parameters has been demonstrated. These resonances correspond to S and P striations observed in experiments. An interpretation of the results is proposed based on an analytical approximation of the numerical solution. Decomposition of EDF into two factors-amplitude and body-is carried out. The amplitude of the EDF is shown to be resonantly dependent on the value of the spatial period. One maximum in the EDF is formed at the value of the spatial period corresponding to the S striation, and two maxima at the value which corresponds to the P striation. The experimental measurements of the EDF in S and P striations with high spatial resolution showed agreement between the theoretical and the experimental results. Resonance effects in the EDF formation are considered based on the linear theory in the weakly modulated electric fields.