Electron beam and plasma modes of a channel spark discharge operation

Parameters of a modified pulsed channel spark discharge (CSD), operating at a repetition rate up to 100 Hz at Ar gas pressures of 10−3 and 10−4 Torr and of the generated electron beam, were studied using different electrical, optical, and x-ray diagnostics. It was shown that efficient (up to ∼74%) transfer of the initially stored energy to the energetic electron beam is realized only at the pressure of 10−4 Torr. Conversely, at the pressure of 10−3 Torr, less than 10% of the stored energy is acquired by the energetic electrons. It was found that the energetic electron beam generation is limited by the expansion of the cathode and anode plasmas and by the formation of plasma inside the gap between the CSD capillary output and the anode. It was also found that the plasma, which acquires the hollow cathode potential, is already formed at the beginning of the CSD operation inside the capillary, and the electron emission occurs from the capillary output plasma boundary. Finally, it was shown that the electron ...