Finite-element analysis of space-charge suppression of electrostatic-induction spray charging

A finite-element analysis of the space-charge suppression encountered durin g the electrostatic-induction spray-charging process will be presented. Thi s paper provides a theoretical framework in support of the experimental stu dies reported elsewhere of the space-charge-limiting barriers of nozzle des ign. Poisson's equation is solved using a finite-element axisymmetric model consisting of 3704 triangular elements and 1946 nodes for various placemen ts of nearby earthed surfaces. Plots of constant potential surfaces in and around the dielectric embedded-electrode charging nozzle are presented. The axial droplet-charging potential gradient at the tip of the liquid jet (al ong the axis of symmetry) depends upon both the positive induction electrod e potential and upon the presence, and substantially upon the spatial exten t of the negatively charged cloud of dispensed droplets.