Effect of the initial phase state of DT-matter on the compression of inertial fusion targets

We investigate the efficiency of inertial fusion target compression, where at the initial time moment the thermonuclear fuel is in a two-phase state and has the form of two adjacent layers — the external DT-liquid layer and the internal DT-ice layer. We study this problem for the fast ignition targets, where the ultimate final density of the thermonuclear matter is of a special importance. We take the simplest type of a fast ignition target, which corresponds to the technical justification of the HiPER Project aimed at demonstrating fast ignition at the compressing laser pulse energy ~100 kJ. Such a target presents a spherical DT-ice shell coated with a thin polymer film. We obtain the dependence of the final target density on the mass fraction of the DT-matter liquid phase and formulate the requirements on the admissible concentration of liquid phase if the decrease in the DT-fuel final density does not exceed 10%. We find the criterion for choosing the laser-pulse duration which provides the minimum decrease in the final density of the target containing DT-matter in the initial two-phase state.