Field Injection Electrostatic Spraying of Liquid Hydrogen

Abstract

Uniform charged liquid hydrogen drops have been produced through field injection electrostatic spraying. The method consists of forming a meniscus of liquid hydrogen at the end of a glass nozzle. A small pressure drop across the nozzle results in a constant volume flow rate of liquid through the nozzle. Field ionization is utilized to inject charge into the liquid. A drop forms and drips off, with the size decreasing with increased charge injection. This mode is referred to as the dripping mode. As the charge on the liquid surface increases, electrostatic forces eventually overcome the surface tension forces. The result is a charged drop thrown off the unstable surface. This mode is named the dribbling mode. As the injection current is increased, the drops become smaller and their frequency increases. Eventually, a charged jet forms which in turn breaks up into small uniform charged drops. This third mode is called the jet mode. A detailed description of the experimental apparatus and results is presented. A qualitative theory is formulated which explains the dribbling mode. A theory, which provides a quantitative description of the jet mode, is presented.