Effects of rod radius and voltage on streamer discharge in a short air gap

Streamer discharge is the inaugural stage of gas discharge, and the average electron energy directly determines the electron collision reaction rate, which is a key parameter for studying streamer discharge. Therefore, taking into account the average electron energy, this work establishes a fluid chemical reaction model to simulate and study the course of evolution of a streamer discharge in a 5 mm rod–plate gap, considering 12 particles and 27 chemical reactions. It introduces the electron energy drift diffusion equation into the control equation, and analyzes the temporal and spatial changes of average electron energy, electric field intensity and electron density with change in rod radius and voltage. The effects of voltage and rod radius on the course of streamer discharge can be reflected more comprehensively by combining the average electron energies. Three different values of 0.3 mm, 0.4 mm and 0.5 mm are set for the rod radius, and three different values of 5 kV, 6 kV and 7 kV are set for the voltage. The influence of an excitation reaction on the streamer discharge is studied. The findings indicate that, as voltage raises, the streamer head's electron density, electric field and average electron energy all rise, and the streamer develops more quickly. When the rod radius increases, the electron density, electric field and average electron energy of the streamer head all decrease, and the streamer's evolution slows down. When an excitation reaction is added to the model, the average electron energy, the magnitude of the electric field and the density of electrons decrease, and the evolution of the streamer slows down. An increase in average electron energy will lead to an increase in electric field strength and electron density, and the development of the streamer will be faster.