Cluster beams in the super-intense femtosecond laser pulse

The evolution of large atomic clusters exposed to a super-intense ultrashort laser pulse is considered. Cluster excitation results from the interaction of its electron subsystem with the laser field. Multiple inner and outer ionization and X-ray emission followed by explosion in clusters irradiated by a laser field are investigated. An increase of the electron temperature in this process and of the charge of the ionized cluster are discussed. The reabsorption of photons in such a plasma is found to be relatively small. The optimal conditions are analyzed for efficient absorption of laser radiation by large clusters. A review is done of the works devoted to X-ray emission and generation of high harmonics of the incident radiation from a hot ionized cluster. The optical depth of the cluster plasma is found to be relatively small for resonance photons of multiply charged atomic ions produced inside the cluster. Expansion and decay of the cluster during and after the laser pulse are analyzed. Nuclear fusion induced by super-intense ultrashort laser pulses in deuterium clusters and in deuterated compounds is considered in detail. The main attention is devoted to the van der Waals clusters consisting of atoms of rare gases, though their properties in super-intense laser field are identical to the properties of metal clusters due to multiple inner and outer ionization.