''Sokol'' high-power 24-channel facility for spherical irradiation of targets

The ''Sokol'' 24-channel neodymium-glass laser facility for spherical irradiation of targets is described. A laser pulse energy E/sub L/ = 300 J at a peak power Papprox.0.4 TW and beam divergence 2αroughly-equal3 x 10-4 rad are attained. The target-irradiation system has a l2-beam geometry and the achieved irradiance uniformity is γroughly-equal10--20% at an irradiation efficiency etaroughly-equal50--70%. In the first stage of the experiments, the efficiency of laser-energy absorption is investigated and the energy absorbed is determined by the ''shock-wave'' technique. A gasdynamic program that takes into account the features peculiar to laser heating of targets is developed and leads to good agreement between the experimental and calculated (R--t) parameters of the shock wave. An analytic expression is obtained to interpolate the gasdynamic calculation results with accuracy approx.1% for absorbed energies from 5 to 50 J and for a residual gas pressure 3--5 Torr