A coating apparatus can include a spray applicator configured to discharge a coating material toward a surface of a workpiece, wherein the spray applicator includes an air shaping orifice, and wherein the spray applicator is configured to generate an electric field between the spray applicator and the workpiece, and a positioning system configured to adjust a position of the spray applicator relative to the surface of the workpiece. It can further include a control system configured to regulate operation of the spray applicator and/or the positioning system to: maintain the spray applicator within a coating distance, maintain a flow rate of shaping air through the air shaping orifice, and maintain an electrical potential of the electric field.

In one embodiment, systems and methods include an electrospray device for atomizing fluids comprising a body defining a resonant microwave cavity, wherein the body comprises a radio frequency inlet configured to inject a radio frequency signal received from a power source into the resonant microwave cavity, wherein the resonant microwave cavity is configured to to amplify a voltage of the radio frequency signal. The device further comprises a field concentrating pole disposed within the resonant microwave cavity configured to concentrate the amplified voltage at a first end of the field concentrating pole to form an electric field. The device further comprises a nozzle disposed at the first end of the field concentrating pole and a fluid supply line configured to provide a fluid disposed within the field concentrating pole and fluidly connected to the nozzle, wherein the fluid supply line is fluidly connected to a fluid source.

An electrostatic spray nozzle assembly is described that includes an induction ring and a fluid tip. The induction ring generates an electrical field for inducing an electrical charge on droplets of a feedstock liquid from the fluid tip that pass through an opening of the induction ring. The induction ring is electrically coupled to an electrical induction field source via a first conductive path provided by conductive surfaces of: a nozzle head holding the induction ring, and a purge gas tube holding the nozzle head. Feedstock flowing through the fluid tip is electrically coupled to a charge carrier source via a second conductive path provided by at least a conductive surface of a fluid tube coupled to the fluid tip. The first conductive path and the second conductive path are electrically isolated by an insulating barrier.