EXPERIMENTAL STUDY OF LASER INTERACTION WITH LOW-DENSITY MATERIALS OF DIFFERENT INTERNAL STRUCTURE IN CONTEXT OF ADVANCED ICF TARGET DESIGNS

摘要

New results obtained in experiments on the "Mishen" facility with laser-irradiated (λ=1.054 μm, τ = 3 ns) low-density porous materials are presented and discussed. A variety of optical and X-ray diagnostic methods was used to characterize physical processes in plane porous samples of different volumetric structure and chemical composition at irradiance I ≤ 10~(14) W/cm~2. The average density of these samples was varied in the range from 1 mg/cm~3 to 30 mg/cm~3. The features of laser light absorption and scattering as well as the efficiency of energy transport inside porous layer were studied in dependence on the incidence angle of laser beam, average density, thickness and target material structure. The plasma formation and energy transport processes are found to differ significantly in laser-irradiated low-density matter of different microstructure (chaotic fibrous structure agar, quasi-regular cellular polystyrene foam). The energy transfer rate and the energy density at the target rear side observed in agar of ～2 mg/cm~3 density are close to those measured in polystyrene foam of ～10 mg/cm~3 density.