INERTIAL FUSION-TARGETS DRIVEN BY CLUSTER ION-BEAM - THE HYDRODYNAMICAPPROACH

Cluster-driven inertial confinement fusion (ICF) is analyzed. A cluste r is defined as a charged supermolecule with a charge of one (or of th e order 1) and with a very high mass number A, so that Z/A much less t han 1. The energy deposition range is shown to be very small (a few mi crometers) for projectiles with a few tens of kev/a.m.u. A significant momentum transfer is therefore possible in its slowing down as it pas ses through matter. In this case, a high hydrodynamic efficiency seems evident. Three relevant models for cluster beam-target interactions a re discussed: (1) the rocket model, where the ablation pressure (P-a) is much larger than the cluster beam direct pressure (II); (2) the ham mer model, where P-a much less than Pi (in this case, two possibilitie s are discussed - an impact interaction between the beam and the targe t, and an impact interaction between one duster and its absorption vol ume); (3) an intermediate model, where P-a similar to Pi (in this regi me, the hydrodynamic efficiency is maximum). Preliminary simulations w ere performed and the general features of the models were confirmed, M ost relevant for ICF, it was found that approximately 75% of the beam energy is converted into X rays, so that the indirect drive is promisi ng in this context.