Study on the lambda=10.6μ heating rediation reflection from a laser-produced plasma

Reflection of focussed radiation of an electroionizing CO2-laser with a plasma mirror from a high-temperature laser plasma on the surface of a solid target has been investigated in the range of densities of heating radiation fluxes approximately 1010-1013 W/cm2. A laser pulse consists of a prepulse of approximately 100 nsec in duration and of the following chain of nanosecond beams. The experiments on measuring the coefficient of reflection by the heating pulse plasma are described both as aperture of a focussing mirror and at the angles exceeding angular dimensions of the focussing system. For the prepulse, the coefficient of reflection to the aperture of the focussing mirror did not exceed several per cent with the total coefficient of reflection to the space angle 2πsub(av) equal to approximately 45 %. An increase in the coefficient of reflection to the aperture of a focussing mirror up to approximately 20 % is observed for nanosecond beams, which is due to the arising of the Mandelstam-Brillouin induced scattering. The investigation of spectral composition of incident and back-scattered radiation has shown that unlike the spectrum of incident radiation, the spectrum of a back-scattered signal can differ essentially for pulses of different duration. The conclusion made on possible mechanisms of reflection of nanosecond pulses with lambda=10.6 μm is in agreement with available data