Estimation of surface charge density under time-dependent external field with new relaxation time constant from dielectric analyzing concept

Traditional EHDA researches concentrated on the behavior of the spray under external dc field. In this research, an attempt was made on acknowledging the time-dependence of the system on the circumstances while ac external field’s being applied. A characteristic time called dipolar relaxation time, which came from the regime of dielectric physics, has been introduced into the current characteristic time system of EHDA process. Such treatment is proceeded under the fact that the permittivity of most material, despite of the deviations caused by temperature changes, being function of time history of external field application, as described in the dipolar part of dielectric relaxation process of molecules. Dramatic deviation of permittivity is expected around RF frequency or higher band of external applied field for most hydrocarbon liquids. This way makes current characteristic time system insufficient or even invalid to describe all phenomena along EHDA process. Research aims at the recognition of the relative importance of dipolar relaxation effect to the original charge relaxation one, which has to be figure out first to allow further experimental acknowledgement of the new characteristic time system.