[en] The development of a high-intensity kilohertz-range pulsed x-ray generator and its application to dental radiography are described. The pulsed x-ray generator consisted of the following major components: a constant high-voltage power supply, a high-voltage main condenser, a hot-cathode triode, a DC power supply for the filament (hot cathode), and a grid controller. The main condenser of 0.5 microF-100 kV in the pulser was charged from 50 to 70 kV by the power supply, and the electric charges in the condenser were discharged to the triode by the grid controller. To be exact, the tube voltage decreased during the discharging for generating pulsed x-rays, yet the maximum value was equivalent to the initial charging voltage of the main condenser. The maximum values of the tube current and the repetition rate were about 0.5 A and 30 kHz, respectively. The pulse width of the x-rays ranged from approximately 20 to 400 micros, and the x-ray intensity with a charging voltage of 70 kV and a total resistance of 5.1 MΩ was about 0.83 microC/kg at 1.0 m per pulse. Using this generator, high-speed dental radiography, e.g., delayed radiography and multiple-shot radiography, was performed

[en] 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 microF, 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 microF 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 charging 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 micros, and the time-integrated x-ray intensity with a charging voltage of 60 kV was approximately 20 microC/kg at 1.0 m per pulse. The characteristic K-series intensity substantially increased according to increases in the charging voltage. High-speed dental radiography was performed by using a laser timing switch and a trigger-delay device