Simulation of two counter-propagating helium discharges at atmospheric pressure

This paper presents 2D simulations showing the dynamics of interaction between two counter-propagating helium discharges at atmospheric pressure. The discharges were generated in two glass tubes separated by a few centimeters in ambient air. First, we applied the same voltage to each electrode wrapped around each discharge tube. Simulation results show that discharges ignite in tubes and then propagate, approaching each other without merging, as observed in experiments. Using the optical emission of discharges, we have determined the minimum distance of approach of counter-propagating discharges. This minimum distance is of the order of the tube diameter, and varies with the tube radius and inversely to the applied voltage. For conditions with different applied voltages on the electrodes, simulation results show a connection of both counter-propagating discharges with an increase in the discharge emission in the interaction region. For conditions with a time delay between the voltage applied on both electrodes, based on the optical emission of discharges, we have observed that counter-propagating discharges approach each other without merging. The minimum distance is of the order of the tube diameter, as in the reference case, without time delay between both applied voltages. However, simulation results show that the electron density in the interaction region between both discharge channels is about one order of magnitude higher than that for the reference case.