A pure inductive regime of pulsed RF discharge in N 2 -He mixtures at 0.2 Torr has been investigated by time resolved Langmuir probe and optical emission spectroscopy. A planar coil ICP with a Faraday shield has been used. Mixture compositions of 5-100% N 2 and duty cycles, T ON = 1-15 ms and T OFF = 15 ms, have been explored. The Langmuir probe analysis evidences a Maxwell electron energy distribution in the discharge and post-discharge, characterized by electron density and temperature that depend on both duty cycle and composition. The vibrational excitation of N 2 (C) state is inferred by the N 2 second positive emissions. Its kinetic analysis reveals the formation of a high vibrational excitation of ground state nitrogen. A vibrational temperature higher than 10 000 K can be reached at the end of the 5 ms discharge pulse on the levels v = 0-3 of the X state. Such a high vibrational temperature slows the post-discharge relaxation of the electron temperature.

The problem of a spherical electrostatic probe in negative ion containing oxygen plasmas is treated by the matching asymptotic expansions technique [A. H. Nayfeh, Perturbation Methods (Wiley, New York, 1973)]. Assuming that the energy relaxation length is much smaller than the local characteristic length, explicit results are obtained in the asymptotic limits, (rp/rD)2≪1,(rp/rS)2≪1, where rD is the Debye radius, rS is the recombination length and rp is the probe radius. The perturbation region divides naturally into a thin space charged sheath, a transitional sheath, and a quasineutral chemically equilibrium plasma. The potential and charged particle density distributions are obtained. The calculated probe characteristic is presented in an analytical form.

Here a self-consistent one-dimensional continuum model is presented for a narrow gap plane-parallel dc glow discharge. The governing equations consist of continuity and momentum equations for positive and negative ions and electrons coupled with Poisson’s equation. A singular perturbation method is developed for the analysis of high pressure dc glow discharge. The kinetic processes of the ionization, electron attachment, and ion–ion recombination are included in the model. Explicit results are obtained for the asymptotic limits: δ=(rD/L)2→0, ω=(rS/L)2→0, where rD is the Debye radius, rS is recombination length, and L is the gap length. The discharge gap divides naturally into four layers with multiple space scales: anode fall region, positive column, transitional region, cathode fall region and diffusion layer adjacent to the cathode surface, its formation is discussed. The effects of the gas pressure, gap spacing and dc voltage on the electrical properties of the layers and its dimension are investigated.

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A perturbation model has been developed to describe the evolution of an expanding plasma sheath around a cathode after a high-voltage negative pulse is applied to the cathode, simulating the conditions in devices such as those used for plasma source ion implantation. The set of governing equations consists of two coupled collisionless fluid equations for ions, and Poisson's equation and Boltzmann's assumption for electrons. The time-dependent, self-consistent expressions for the potential, ion density and ion flux are obtained and compared successfully with experimental and simulation results.