Threshold parameters of vacuum arcs with W-fuzz cathodes

•A technique has been developed to investigate the threshold current for triggering vacuum arcs with W-fuzz cathodes.•The formation of a nanostructured fuzz layer on a tungsten surface reduces the threshold current by an order of magnitude compared to virgin tungsten surfaces.•The arc operation time at currents of tenths of an ampere is in the microsecond range. An experimental technique was developed and performed to investigate the threshold currents and operation times of vacuum arcs with tungsten cathodes having a nanostructured (so-called “fuzz”) surface. The fuzz layer, pre-formed due to exposure of the tungsten samples with helium plasma, reduced the threshold current for arc initiation by an order of magnitude. For currents of tenths of an ampere, the average arc operation time was in the microsecond range. The experimental data were interpreted using the explosive emission (ecton) model of a vacuum arc cathode spot.