This paper concerns theoretical and experimental investigations of the effect of a conductor coating on the onset voltage of a corona on overhead transmission-line conductors. The onset voltage for a self-maintained discharge on the basis of discharge physics is evaluated. This calls first for accurate calculation of the electrical field in the vicinity of a coated conductor and its correlation to the field values near a bare conductor of the same radius. The well-known charge simulation technique is used for field calculation. The calculated electrical field values are utilized in evaluating the onset voltage of positive and negative coronas on bare and coated conductors. The onset voltage increases with a conductor coating. The calculated onset-voltage values agreed satisfactorily with those measured for laboratory models and full-scale test lines.

This paper is aimed at investigating how the characteristics of corona and silent discharges including ozone generation are influenced by geometry of the discharge reactor. The corona discharges have been generated in coaxial wire-cylinder and wire-duct reactors stressed by dc and ac voltages. The silent discharges have been generated in the same reactors in addition to tubular reactors under ac voltage after pasting a dielectric barrier on the ground electrode of the reactors. The reactors were fed by dry air flowing at atmospheric pressure and temperature. The pulse characteristics of silent discharges are compared with those of ac corona discharges. The current-voltage and the ozone generation characteristics of silent and ac discharges are recorded. These characteristics depend significantly on the geometry of the reactor irrespective of the discharge type. NomenclatureC ozone concentration, ppm d width of the discharge gap, mm dV /dt time derivative of voltage V , kV s −1 P discharge power, W Q air flow-rate through the reactor, litre min −1 r radius of the discharge wire, mm STP standard temperature and pressure conditions V o onset voltage of the discharge (peak value), kV V p applied voltage (peak value), kV

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The propagation of electrostatic ion acoustic waves (IAWs) in a homogeneous, unmagnetized, and collisionless plasma system composed of two positive ions and superthermally distributed electrons is investigated. The three dimensional Kadomtsev-Petviashvili (KP) equation has been derived using the reductive perturbation analysis to describe the dynamics of the weakly nonlinear behavior of electrostatic IAWs in the Venusian ionosphere near the terminator region. A symbolic computational Painlevé analysis is employed to get various solutions of the KP equation. The stability of the localized structures solution against the variation in the transverse direction has been discussed. The condition for the localized pulses existence in the presence of transverse perturbations is examined via the pseudo-potential approach. Numerical studies to elaborate on the physical plasma parameters’ effects on the structural characteristics of nonlinear cnoidal, periodic, and soliton waves are graphically displayed. The model predicts a compressive supersonic IAWs can propagate in the Venusian ionosphere in agreement with the observations.

The modification of the ion-acoustic wave dispersion under the action of a high frequency electric field was studied experimentally, the wave propagating along and against the plasma stream. The frequency of the field amounted to approximately half the electron plasma frequency. It was found that the phase velocity of the ion wave and the plasma drift velocity decrease as the effective high frequency field power increases