Charge Composition of Ions in a Cluster Plasma Formed under the Action of a High-Power Laser Pulse

A model describing the ionization of atoms and ions in a cluster under irradiation by a short laser pulse has been constructed. It is shown that the electron-impact ionization weakly affects the final charge composition, and the main mechanism of ion formation in the cluster is the over-barrier ionization by an electric field. The electric field acting on atoms and ions is the result of combined action of the external laser field and the intrinsic electric field of the cluster. The key parameters of the cluster beam and the laser pulse, which determine the properties of the charge composition of the cluster plasma, have been established.