Compact monochromatic flash x‐ray generator utilizing a disk‐cathode molybdenum tube

The high‐voltage condensers in a polarity‐inversion two‐stage Marx surge generator are charged from −50 to −70 kV by a power supply, and the electric charges in the condensers are discharged to an x‐ray tube after closing gap switches in the surge generator with a trigger device. The x‐ray tube is a demountable diode, and the turbo molecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Clean molybdenum K α lines are produced using a 20 μm‐thick zirconium filter, since the tube utilizes a disk cathode and a rod target, and bremsstrahlung rays are not emitted in the opposite direction to that of electron acceleration. At a charging voltage of −70 kV, the instantaneous tube voltage and current were 120 kV and 1.0 kA, respectively. The x‐ray pulse widths were approximately 70 ns, and the generator produced instantaneous number of K α photons was approximately 3 × 10 7photons ∕ cm 2 per pulse at 0.5 m from the source of 3.0 mm in diameter.