Charge losses in expanding plasma created by a XeCl laser

The emission of multiply charged Cuq+ ions from a plasma produced by 308-nm excimer laser is analysed with respect to the distance from the irradiated target. The critical zone, outside which the charge states of ions of the expanding plasma are frozen, was determined to be about 20 cm from the target. This value was estimated using a charge-freezing criterion expressed by a distance dependence of the total charge carried by the ions QL-2, which describes the dilution of plasma by its expansion into a vacuum without collisional recombination processes.