Evolvement of deuterium clusters in ultrashort ultraintense laser field

With large deuterium clusters produced in a supersonic expansion of high pressure gases into vacuum through a cone nozzle, experiments have been carried out to investigate the evolvement of deuterium clusters in ultrashort ultraintense laser field based on the SILEX-Ⅰ laser system. Tens keV deuterium ions were observed. The energy spectrum of these ions agrees with the Coulomb explosion model. It is found that distribution of the energy spectrum is determined by the average size of clusters. A part of electrons escape from the clusters by above threshold ionization after laser irradiation, and then collision ionization starts to dominate with the enhanced screening effect produced by the initial ionization electrons．