Simulation of Trichel streamer pulse characteristics at various air pressures and humidity

Trichel streamer pulses have been simulated at various air pressures and humidities. A flux-corrected transport algorithm based on a non-uniform mesh was applied to solve the continuity equations and Poisson´s equation in a fluid model to calculate the negative streamer pulse waveforms. The values of the various coefficients for humid air, considered as a mixture of air and water vapor, were estimated by linear interpolation from the values for the separate ´gases´. The simulation results agreed with the trends in the experimental results of our previous study: the average amplitudes of the negative streamers decreased with a rise of pressure or humidity. The decrease of current amplitude with the rise of pressure was mainly due to the decrease in the electron density and hence the conductivity of the streamer channel as a result of the increase of attachment rate.