Method and apparatus for feedback controlled electrospray

A feedback control system for an electrospray nozzle which is held at ground potential, having a nozzle tip which is displaced from a counterelectrode which communicates with a source of electrical potential, comprising

• a source of light, with focusing optics focused to intersect one or more of the liquid cone, jet and plume of the fluid exiting the electrospray nozzle,
• one or more photo detectors, configured individually or in an array and disposed to detect scattered light patterns, transmitted light patterns or both, passing through, reflected by or emitted from said liquid discharged from said electrospray nozzle as a result of the intersection of light from said source of light with said liquid, and generate photo-electronic signals in response thereto,
• an electronic detection and amplification system adapted to convert said photo-electronic signals to electronic signals,
• a first computer or microprocessor system programmed or adapted to interpret said electronic signals, and
• a second computer or microprocessor system communicating with said first computer or microprocessor system, and adapted to generate a signal to a controller which will either adjust the distance between said electrospray nozzle and a counterelectrode by displacing said nozzle, said counterelectrode, or both, or change the voltage applied to said counterelectrode with respect to said nozzle.