Production of a pulsed high-density electron beam by channel spark discharge

The characteristics of the generation of a high-energy electron beam by a channel spark discharge were investigated. After a hollow cathode discharge in lowpressure nitrogen gas, a pulsed high voltage of -8 to -20 kV from a 2- to 32-nF capacitor initiated a channel spark discharge in a glass tube with an internal diameter of 8 mm. Using a newly designed experimental apparatus, it was shown that a high-energy electron beam was produced in the pressure range from 0.4 Pa to 3.1 × 10-3 Pa in the vacuum chamber. Varying the internal diameter at the end of the glass tube between 16.8 mm and 0.1 mm controlled the diameter of the electron beam. Measurements of the energy distribution of the electron beam revealed that the mean electron energy was approximately 12 kev at the charging voltage of the 20-kV capacitor. The optimum power density of 1.4 × 108 W/cm2 was obtained by using a glass tube with an internal diameter of 2.7 mm at the end at a pressure of 0.4 Pa. © 2001 Scripta Technica.