Positive corona discharge current in a thin wire-cylinder electrode configuration

The positive corona discharge current in a thin wire-cylinder pair of parallel electrodes has been studied, under high-voltage dc application. Experiments have been conducted to determine the relationship between the electric corona discharge current and the applied voltage, as well as the dependence on geometrical characteristics of the electrodes such as the electrode length, the electrode gap and the emitter and collector radii. The results have shown that the discharge current is related to the applied voltage by a quadratic expression which is in good agreement with the well-known Townsend's general formula for the corona current. Parametric analysis has shown that the positive corona discharge current per unit electrode length decreases with the emitter radius and the electrode gap. On the other hand, an increased collector radius results in increased discharge current with respect to the applied voltage. Based on the experimental results, an expression for the discharge current, as a function of the applied high dc voltage and geometrical characteristics of the electrodes could be derived. This formula resembles similar formulae found in literature for other electrode arrangements and provides a very good approximation of experimental values.