Electrostatic metallic spray theory

Abstract

A statistical model for the description of an isolated cloud of electrostatically generated droplets is developed. The droplet charging process is assumed independent of droplet population density consistent with high fluid conductivity and maximal charging levels. It is found that charge distribution is describable by Fermi-Dirac statistics and droplet number distribution by Maxwell-Boltzmann statistics. Evaluation of molten copper sprays reveals that the smaller the droplet cloud mass the higher the overall charge-to-mass ratio will be. Charge-to-mass ratio is found to vary approximately as the inverse square of droplet radius. The smaller the droplet the closer it can in general approach the Rayleigh criterion charge limit. The influence of emission-limited charging was found to be unimportant for the cases studied. The model indicates the possibility that microscopic distributions of charge and mass can be inferred from knowledge of total charge and mass.