Field injection electrostatic spraying of liquid hydrogen

Uniform charged liquid-hydrogen drops are produced using the method of field injection electrostatic spraying. This method consists of forming a meniscus of liquid hydrogen at the end of a glass nozzle and injecting charge into the liquid using a sharp electrode raised to a high voltage. A small pressure drop across the nozzle results in a constant volume flow rate of liquid through the nozzle allowing a drop to form and drip off. As the amount of charge injection increases with the raised needle electrode voltage, the drop size decreases due to the increased electrostatic forces compensating for the surface tension forces. As a result, the drops drip off at an increased frequency. Eventually a charged jet forms which in turn breaks up into small uniform charged drops. A detailed description of the experimental apparatus is presented. Experimental results are presented and discussed.