Abstract: An EDM method and apparatus for machining a workpiece electrode with a tool electrode wherein a solid-state switching type EDM generator provides a succession of machining current pulses across a machining gap formed between the electrodes flooded with a liquid dielectric, preferably distilled water or a weakly conductive aqueous liquid, through a gap discharge circuit. The total value of stray capacitances in the gap discharge circuit is limited to be less than 0.01 microfarad, preferably at most 0.005 or 0.001 microfarad, to control a rise of peak current at the leading edge of each individual machining current pulse. The gap current at the leading edge of a pulse may be sensed and discriminated to provide a control signal which acts on the DC power supply to control the output voltage thereof so that the initial rise of peak current may be maintained substantially constant, irrespective of a change in the stray resistance in the gap discharge circuit during a given course of machining operation.

Abstract: An electron beam processor with an energy storage line and matched field emission diode that define a high energy electron beam generator. A transport system positions a specimen to be thermally processed in a processing station. Energy stored on the line is discharged through the diode and the resulting high energy beam impacts upon the specimen for thermally processing selected regions thereof.

Abstract: An arrangement for detecting abnormal concentration of electrical discharges between a travelling wire electrode and a workpiece in a travelling wire EDM apparatus. The abnormal electrical discharge detector of the invention comprises a circuit measuring the voltage across a pair of contacts supplying machining current to the electrode wire. The length of the electrode wire between the two contacts forms a pair of variable resistors connected in a branch of a Wheatstone bridge circuit. The voltage measuring circuit, connected across a diagonal of the bridge, in turn controls some of the machining parameters such as to prevent damages, as for example rupture of the wire electrode, when an abnormal concentration of electrical discharges is detected at a given point of the machining zone between the wire electrode and the workpiece.