Abstract: The use of high voltage relays in variable pulse width magnetron type triggering circuits are avoided by the use of two separate pulse-forming networks. In addition, two separate banks of charging capacitors and switching transformers are employed. Separate SCR's are employed to apply charging current to either the first or the second bank of storage capacitors. Additional SCR's are employed to initiate the triggering sequence for the selected pulse-forming network and associated circuitry. The selected pulse length might be microsecond or one-quarter microsecond, with pulse repetition rates of 1,000 to 2,000 pulses per second. Accordingly, the duty cycle could be in the order of 0.001%, or less, but the output pulse power during the "on" time for the circuit might be in the order of several hundred kilowatts. During each cycle of operation, the two switching transformers and the output pulse transformer, which are both of the square or rectangular hysteresis loop type, are reset.

Abstract: In the shaping of ductile metal sheet, especially superplastic alloy sheet, by the application of pressure differentials, the peripherally clamped sheet is first urged, by pressure differential in one direction, against a female molding surface to form a partially shaped bubblelike preform and then a male mold is advanced towards the sheet from the other side and a reverse pressure differential is applied to cause the pre-form to conform to the shape of that mold. The active area forming the pre-form may be restricted by an apertured plate adjacent the clamping plane, matching the overall outline of the body, and a plate the other side matching closely the profile of the body may confine the action of the reverse pressure only to that part of the sheet that engages the progressively increasing part of the male mold that extends through the clamping plane so that the sheet locks progressively onto the sides of the male mold to obtain an approximately uniform wall thickness in the finished body.