INERTIAL FUSION-TARGETS DRIVEN BY CLUSTER ION-BEAM - THE HYDRODYNAMIC APPROACH

Cluster-driven inertial confinement fusion (ICF) is analyzed. A cluster is defined as a charged supermolecule with a charge of one (or of the order 1) and with a very high mass number A, so that Z/A much less than 1. The energy deposition range is shown to be very small (a few micrometers) for projectiles with a few tens of kev/a.m.u. A significant momentum transfer is therefore possible in its slowing down as it passes through matter. In this case, a high hydrodynamic efficiency seems evident. Three relevant models for cluster beam-target interactions are discussed: (1) the rocket model, where the ablation pressure (P-a) is much larger than the cluster beam direct pressure (II); (2) the hammer model, where P-a much less than Pi (in this case, two possibilities are discussed - an impact interaction between the beam and the target, and an impact interaction between one duster and its absorption volume); (3) an intermediate model, where P-a similar to Pi (in this regime, the hydrodynamic efficiency is maximum). Preliminary simulations were performed and the general features of the models were confirmed, Most relevant for ICF, it was found that approximately 75% of the beam energy is converted into X rays, so that the indirect drive is promising in this context.