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Various characteristics of a plasma flash x-ray generator having a cold-cathode radiation tube and its application to high-speed soft radiography are described. The x-ray generator employs a high-voltage power supply, a low-impedance coaxial transmission line with a gap switch, a high-voltage condenser with a capacity of about 200 nF, a turbo-molecular pump, a thyristor pulser as a trigger device, and a flash x-ray tube. The high-voltage main condenser is charged up to 60 kV by the power supply, and the electric charges in the condenser are discharged to the tube after triggering the cathode electrode. The flash x-rays are then produced. The x-ray tube is of a demountable triode which is connected to the turbo molecular pump with a pressure of approximately 1 mPa. As the electron flows from the cathode electrode are roughly converged to the target by the electric field in the tube, the plasma x-ray source which consists of metal ions and electrons is produced by the target evaporating. Both the tube voltage and current displayed damped oscillations, and their peak values increased according to increases in the charging voltage. In the present work, the peak tube voltage was almost equivalent to the initial charging voltage of the main condenser, and the peak current was less than 30 kA. In this experiment, we employed four types of plasma targets as follows: (1) single target, (2) coaxial double target, (3) alloy target, and (4) plate target. When the single target in conjunction with the monochromatic filter was employed, high-intensity quasi- monochromatic x-rays were obtained. Next, the characteristic x-ray intensities from the outer target increased in the case where the double target was used. By using the alloy (copper tungsten) target, the x-ray intensities of the copper K-series lines increased. Finally, when the linear plasma x-ray source was formed by using the plate target, the bremsstrahlung x- rays were absorbed and were converted into florescent rays, and high-intensity characteristic x-rays were produced.
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