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The construction and the radiographic characteristics of a plasma flash x-ray generator having a molybdenum-target (anode tip) triode are described. This generator was primarily designed in order to perform soft radiography in dental medicine and employed the following essential components: a high-voltage power supply, a low-impedance coaxial transmission line with a gap switch, a coaxial oil condenser of 0.2 (mu) F, a turbo-molecular pump, a Krytron pulser as a trigger device, and a flash x-ray tube. The high-voltage main condenser of 0.2 (mu) F was charged from 40 to 60 kV by the power supply, and the electric charges in the condenser were discharged to the tube after closing the gap switch. Because this tube employed a long target, the plasma x-ray source which consists of molybdenum ions and electrons was easily produced by the target evaporating. The maximum tube voltage was nearly equivalent to the initial charge voltage of the main condenser, and the maximum current had a value of about 25 kA with a charging voltage of 60 kV. The average width of flash x rays was less than 1 microsecond(s) , and the time-integrated x-ray intensity with a charging voltage of 60 kV was approximately 20 (mu) C/kg at 1.0 m per pulse. The characteristic K-series intensity substantially increased according to increases in the charged voltage. High-speed dental radiography was performed using a laser timing switch and a trigger-delay device.
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