Pulsed electron beam sources for material ablation

As an alternative to the pulsed laser ablation, the material ablation made with pulsed electron beams was also studied since several years. In transient hollow cathode discharges (THCD) pulsed electron beams of tens - hundreds of A, in tens of ns with energies up to tens of keV are produced, which propagate in a self-focused way due to space charge neutralization. Typical discharges are the pseudospark and channel-spark discharges, and the preionized controlled open-ended hollow cathode discharge (PCOHC). In this work two compact electron beam sources are studied, PCOHC and channel-spark. The PCOHC discharge has some specific characteristics: an open-ended hollow cathode, a preionization discharge in the cathodic region and an overvoltage functioning mode. For a given pressure and for an optimized tuning of the preionization discharge, a pulsed electron beam is produced, similar to that of the pseudospark, but with the advantage of an excellent reproducibility. The channel-spark discharge has similarities with the pseudospark discharge: a closed hollow cathode with an axial borehole, a trigger discharge inside the hollow cathode and a self-breakdown functioning mode. The major difference consists in the presence of a dielectric capillary tube between the hollow cathode and the anodic region of the discharge. (authors)