Computer modelling of Trichel pulses in air

A program has been developed to model negative corona pulse trains (Trichel pulses) in air. A spherically-symmetrical system comprising a small negatively-charged spherical electrode concentric with a large grounded spherical electrode was used. This system facilitates calculation of fields and charged particle densities in the air-gap as compared with the conventional point/plane electrode where only the axial field is usually considered. To test the program, an equivalent practical geometry was used: a hemispherically-tipped electrode concentric with a large concave hemispherical electrode. Recordings of pulse rates over a range of pressures from 0.2 to 1 bar were made over the voltage range for which corona pulses were produced: these were found to give good agreement with the pulse rates obtained at the same voltages and pressures from the simulation. The shape of the individual pulses was also closely similar to those recorded.