REPETITIVE FLASH X-RAY GENERATOR HAVING A HIGH-DURABILITY DIODE DRIVEN BY A 2-CABLE-TYPE LINE PULSER

The fundamental studies of a repetitive soft flash x-ray generator hav ing a high-durability diode for high-speed radiography in biomedical a nd technological fields are described. This generator consisted of the following essential components: a constant negative high-voltage powe r supply, a line-type high-voltage pulser with two 10 m coaxial-cable condensers, each with a capacity of 1.0 nF, a thyratron pulser as a tr igger device, an oil-diffusion pump, and a flash x-ray tube. The x-ray tube was of a diode type which was evacuated by an oil-diffusion pump with a pressure of approximately 6.7 X 10(-3) Pa and was composed of a planar tungsten anode, a planar ferrite cathode, and a polymethylmet hacrylate tube body. The space between the anode and cathode electrode s (AC space) could be regulated from the outside of the tube. The two cable condensers were charged from -40 to -60 kV by a power supply, an d the output voltage was about -1.5 times the charged voltage. Both th e first peak voltage and current increased according to increases in t he charged voltage, and the maximum values of the voltage and current were about 90 kV and 0.72 kA, respectively. The pulse widths had value s of less than 100 ns, and the maximum x-ray intensity was approximate ly 1.1 muC/kg at 0.5 m per pulse. The repetition rate was less than 54 Hz, and the maximum focal spot size was about 2.0 X 2.5 mm.