Effect of gas ionization on interphase interaction of adjacent oppositely charged droplets

Abstract

The microscopic evolution behavior of the interphase interaction between adjacent oppositely charged droplets in air and helium environments is investigated. By means of high-speed microscopy with high spatial and high temporal resolution, a special attention has been paid to the interphase morphology characteristics of oppositely charged droplets with different conductivities and applied voltages, and the dynamic evolution behaviors of noncontact bounce and noncontact breakup under the influence of gas ionization are discussed in detail. The results show that noncontact bounce occurs for low-conductivity droplets, whereas noncontact breakup occurs for high-conductivity droplets as the applied voltage increases gradually and that the occurrence of gas-phase ionization and reaching the Rayleigh limit dominate the changes of interphase interaction behaviors. Droplets of high conductivity mean greater minimum pole spacing when the noncontact bounce or breakup behavior occurs. With the increase of conductivity, the voltage required for noncontact breakup gradually decreases, while the occurrence of noncontact breakup behavior in a helium environment is relatedly lagging. Meanwhile, the minimum pole spacing of noncontact breakup is always greater than that in an air environment, and the changes of the minimum pole spacing in air and helium environments indirectly prove that the noncontact bouncing behavior of adjacent charged droplets is induced by gas ionization. We introduce here the special interphase interaction of adjacent oppositely charged droplets. The occurrence of gas-phase ionization and reaching the Rayleigh limit dominate the changes of interphase interaction behaviors, and the significant differences of the minimum pole spacing d in air and helium environment indirectly prove that the noncontact bouncing behavior of adjacent charged droplets is induced by gas ionization.