Operating voltage of a W-fuzz cathode arc and the mass/charge composition of the arc plasma depending on the fuzz thickness

•Fuzz formation leads to a significant decrease in the arc operating voltage.•This is due to a decrease in the energy expended for evaporation of tungsten atoms.•The fuzz thickness weakly affects the arc plasma voltage and mean ion charge. The arc operating voltage and the mass/charge composition of the arc plasma were measured for W-fuzz samples with different fuzz thicknesses at different numbers of arc pulses. It was found that the formation of a fuzz structure led to a significant decrease in the arc operating voltage within the first few arc pulses. With an increase in the number of pulses, the operating voltage and the mean charge of tungsten ions in the arc plasma increased to values characteristic of conventional tungsten cathodes. The obtained experimental data were analyzed theoretically using an empirical cohesive energy rule and a magnetohydrodynamic model of the ionization processes occurring in a cathode plasma jet.