Lawrence Berkeley National Laboratory

There are divergent results in the literature on the (in)dependence of the ion velocity distribution functions on the ion charge states. Apparently, most time-of-flight methods of measurements indicate independence whereas most measurements with electrostatic analyzers state the opposite. It is shown here that this grouping is coincidental with investigations of pulsed and continuous arcs. All results can be consolidated by taking ion-neutral interaction into account, especially charge exchange collisions with the metal neutrals produced by the arc itself. The velocity distribution functions are independent of charge state when produced at cathode spots but become charge-state dependent when the plasma interacts with neutrals.