Far-field characteristics of ionic wind induced by needle-ring and single-electrode corona in ambient air

In this work we investigated the far-field characteristics of ionic wind induced by the DC corona discharge of a needle-ring and/or single-needle electrode configuration in ambient air. Wind velocity, net ion flux and their spatial distribution were measured under various conditions and ion kinetic behavior was analyzed with an electrodynamic model. The results show that the ionic wind in the needle-ring corona is due to the inertia of ions accelerated between electrode gap, while the ionic wind in the single-electrode corona is formed by ions accelerated outside the needle, propagating as far as about 100 cm in space. Wind velocity depends on the distance, moving direction, total corona current, air density and ion mobility as well as the voltage polarity. In an axial axis, the ionic wind speed decreases with distance as a function of inverse square root, while the ion flux decreases with distance as an inverse quadratic function for both coronas. The electrodynamic model can well describe the motion of the ions as well as the ionic wind formation, revealing results being highly consistent with the experiment.