Clean monochromatic x-ray irradiation from weakly ionized linear copper plasma

Abstract

In the plasma flash x-ray generator, a 200-nF condenser is charged up to 50 kV by a power supply, and flash x-rays are produced by the discharging. The x-ray tube is a demountable triode with a trigger electrode, and the turbomolecular pump evacuates air from the tube with a pressure of approximately 1 mPa. Target evaporation leads to the for- mation of weakly ionized linear plasma, consisting of copper ions and electrons, around the fine target, and intense Ka rays are produced us- ing a 10-mm-thick nickel filter. At a charging voltage of 50 kV, the maxi- mum tube voltage is almost equal to the charging voltage of the main condenser, and the peak current is about 15 kA. When the charging voltage is increased, the linear plasma forms, and the copper Ka inten- sities substantially increase. The Ka lines are quite clean and intense, and hardly any bremsstrahlung rays are detected at all. The x-ray pulse widths are approximately 700 ns, and the time-integrated x-ray intensity has a value of approximately 20 mC/kg at 1.0 m from the x-ray source with a charging voltage of 50 kV. © 2005 Society of Photo-Optical Instrumentation