Wildlife management in the National Parks

A source of intermittent unipolar voltage pulses is connected across an electrode and a workpiece to be machined, defining between them an erosion gap which is swept by a continuously moving, slightly electrolytic liquid. With suitable spacing of the pulses, the flow of the liquid removes excess ions and detritus from the erosion gap while its conductivity limits the voltage peak at the beginning of each discharge. To insure an even distribution of the flow, the liquid is admitted to the gap from above through one or more passages formed in the electrode, spreading symmetrically in opposite directions.