Maximizing ion-driven gas flows

Gas flows of modest velocities are generated when an organized ion flux in an electric field initiates an ion-driven wind of neutral molecules. When a needle in ambient air is electrically charged to a potential sufficient to produce a corona discharge near its tip, such a gas flow can be utilized downstream of a ring-shaped or other permeable earthed electrode. In view of the potential practical applications of such devices, as they represent blowers with no moving parts, we investigate methodologies for increasing their flow velocities, both theoretically and by experiments. The parameters evaluated include divergence of electric field lines, avoidance of regions of high curvature on the second electrode, control of atmospheric humidity, and the use of linear arrays of stages, terminating in a converging nozzle. We find that the behavior of ionic wind generators is analogous to that of fans and our modifications have more than doubled the maximum previously reported ion-driven wind velocities.