Energetic ions and electrons produced in a hollow cathode vacuum spark

A vacuum spark having a tungsten pointed anode and a hollow cathode is feeded by a small Marx generator (11). It produces energetic beams of tungsten ions (E= 0.5 to 70 keV) and electrons beams in the first ignition phase. The electrons produce. an X-ray emission through Bremsstrahlung in the Tenon insulator and by Auger cascade in relation with particle emission. In the second phase. when the applied electric field is low and the current intensity is high, the electrons give rise to W (Lα and Lβ) X-ray emission. The mechanism of this last part is ascribed to interactions either with the massive anode or a plasma surrounding the anode. In the case of dense plasma interaction. the emission is of the same type as observed in laser-plasma interaction. Spots of X-rays are also observed which may originate from pinching or interaction with drops or dust particles in the interelectrode spacing. Experimental results obtained using X-ray imaging are discussed.