PARAXIAL CORONA DISCHARGE .2. SIMULATION AND ANALYSIS

The authors deal with the theory, numerical analysis and simulation of positive-corona air discharges in noncoaxial cylinders. A finite-difference method is developed which is then modified for forward extrapolation. Experiments described previously, using various paraxial offsets and voltages, are simulated using the Townsend/Kaptzov field assumption at the inner conductor and adopting a hypothesis for the corona current distribution from various alternatives. Good correlations are found between the measured and calculated current and electric field distributions at the outer cylinder. Calculation errors are carefully assessed. It is found that the Laplacian and Poissonian field shapes are very different and exhibit field-crossover effects. The simulated solution allows an assessment of the Deutsch approximation to be made for this geometry. Variations between the Laplacian and Poissonian fields can differ by an order of magnitude which shows the approximation to be, at best, the starting point for a numerical solution. The finite-difference algorithm developed is quite general and can be adapted to other two-dimensional charge-flow problems.