Investigation of repetitive high quality electron beam from a pseudospark

Abstract

Summary form only given. An experimental investigation of a pseudospark-produced electron beam is being performed. The pseudospark chamber consists of modular six gap brass and insulator disks stacked between a hollow cathode and an anode. The anode has a 3.2-mm on-axis hole for the beam extraction. External capacitances are added to the self-capacitance of the pseudospark chamber to determine the beam behavior with different stored energies. The pseudospark is operated in the 5-25-kV voltage and 30-70-mtorr pressure ranges. A breakdown curve similar to Paschen's curve (for two parallel electrodes) was obtained for the pseudospark. The breakdown occurs in two phases. During the first phase, the discharge voltage drops slowly while the discharge and beam current are small. In the second main breakdown phase, the discharge voltage drops to almost zero and the discharge and beam current rise to large values. For C ext=980 pF, an electron beam with a current of 150 A and an average energy of 25 keV is produced. The RMS emittance of the beam measured at an axial distance of 9 cm from the anode is 65 mm-mrad. This corresponds to a beam brightness of 1.0t1011 A/(m2-rad2), which characterizes the pseudospark as a high brightness source