Research on the Prebreakdown Current of the Laser-Triggered Vacuum Switch

The prebreakdown current flowing in a laser-triggered vacuum switch (LTVS), investigated in this paper, is below the threshold voltage, where the switch becomes conducting. The laser irradiates in a short time the sintered KCl and Ti target of the vacuum switch and produces an initial plasma. The prebreakdown currents are measured in two different electrode geometries (planar and multirod) at both polarities and analyzed with respect to the ion and electron interactions with the electrodes. It is found that the peak value of the prebreakdown current increases with the applied voltage across the LTVS until 60 to 80 V, where it turns instantly into the conducting state. The multirod and planar LTVSs show different prebreakdown currents at different polarities, which is related to the condition of becoming conducting.