Time-Resolved Ion and Electron Current Measurements in Pulsed Plasma Sheaths

In this paper, time-resolved Langmuir-probe measurements of both electron and ion currents in the transient sheath region adjacent to a plasma ion implantation target pulsed to negative high voltages are reported. A fast (i.e., greater than the ion-acoustic speed) initial sheath expansion is observed followed by a slower propagation at the ion-acoustic speed into the bulk plasma. It has been observed that the ion density exhibits perturbation near the ion plasma frequency several microseconds prior to its depletion