Pseudospark as an electron beam source

Summary form only given, as follows. The authors have constructed a modular-type multigap pseudospark chamber to investigate the electron beam produced. The chamber consists of a hollow cathode and 65-mm-diameter brass electrodes with a 3-mm-diameter hole on center and plexiglass insulating washers stacked alternately. The capacitance of the device has been adjusted from the interelectrode capacitance 11 pF to 760 pF by adding external capacitors. The chamber was charged up to 30 kV, and then the gas pressure was slowly increased until breakdown occurred. At a breakdown voltage of 25 kV, a peak discharge current of 640 A was measured and an electron beam of 190 A and 20 ns FWHM was extracted through the anode hole. Inside the drift tube, filled with the same 40 mtorr of argon gas as the chamber, the electron beam propagated farther downstream. As the beam propagated, the beam current dropped to 120 A and 60 A at 3 cm and 30 cm from the anode, respectively. The spatial profile of the beam was determined. At an axial distance of 3 cm from the anode a beam diameter of 1.5 mm FWHM was found.<>