Spatial-angular scattering of laser radiation by plasma of sulfur, tungsten, aluminum, and copper targets

Studies of laser radiation scattering by plasma generated from solid planar targets of S, W, Al, and Cu were conducted, providing information on the scattering directivity diagrams in two mutually perpendicular planes. In the case of S and Al targets, diagrams including the self-emission of plasma in the wavelength range of 400–1900 nm were also obtained for comparison. The experimental results and theoretical estimates demonstrate that the plasma emission and expansion are close to spherical, while the laser radiation scattering is most intense within the solid angle of the focusing lens aperture. The resulting diagrams show a similar scattering of radiation by plasma in the vertical and horizontal planes. In the case of W, Al, and Cu targets, as the laser pulse energy increases, the relative share of scattered radiation decreases, which indicates the presence of anomalous absorption of laser radiation in the plasma. Whereas for sulfur plasma, the relative share of scattered radiation increases, and this can be explained by the influence of parametric instabilities on the anomalous absorption.