Cluster dynamics in strong fields and its application to fusion science

Key physical processes of laser-cluster interaction, i.e. the absorption of laser energy and the highly efficient energy conversion to cluster ions and resulting rapid expansion, are theoretically and computationaly investigated. Depending on the interrelationship between cluster size a and the electron excursion length ξe (which is related to the laser field amplitude), the expansion characteristics is categolized into the Coulomb explosion (a << ξe) and alternative hydrodynamic ambi-polar expansion (a >> ξe), revealing different feature in the ion energy distribution. The cluster state is small particle system where the level of fluctuation is high compared with that of usual gas and/or plasma. Due to this fact, the interacion is affected by the microscopic cluster distributions, so that the observed quantity has to be determined from the statistical average over possible disordered probabilistic distributions. An application of the laser-cluster interaction to nuclear fusion for short pulse high flux neutron generation is proposed and the feasibility to obtain 1012 - 1013/cm3 per laser shot is discussed