Action Of Powerful Laser Pulses Research Articles

Investigation of propagation dynamics of material deformations caused by laser pulse action

The mechanoluminescent materials attract increasing attention of scientists due to their capability of visualizing the mechanical stresses and deformations experienced by them. The deformations of materials arising under the action of powerful laser pulses were studied. The composite mechanoluminescent materials based on the polymer and phosphor powder were used for visualization and registration of deformation evolution dynamics. The mechanoluminescent materials were deposited on the surface of the materials under study. It has been shown that the spatial distribution of glow intensity of the mechanoluminescent layer and the rate of its change make possible judging the value and rate of material deformation under laser pulses.

On possibility of high-power terahertz emission from target under the action of powerful laser pulses

The possibility of terahertz (THz) emission from a target irradiated by short (∼0.1 ns) high-intensity (I ∼ 1018–1019 W/cm2) laser pulses has been studied by numerical simulations using a relativistic electromagnetic PIC code. The laser pulse action on the target generates plasma and the runaway electrons form a virtual cathode, which oscillates in the intrinsic field of electrons and the field of plasma ions. These oscillations account for the emission of radiation in a THz range. The generation efficiency is about three times as high as that in the absence of ions (according to the conventional reditron mechanism). Explanation of the observed phenomena is proposed.

Nonlinear spectroscopy of photocoloured polytungstic acid nanocomposites

Picosecond absorption spectroscopy was used in an investigation of nonlinear optical processes in nanostructured composites based on polytungstic acid, which were photocoloured by preliminary UV irradiation. The absorption bands responsible for the photocoloration and associated with intervalent charge transfer were bleached by the action of powerful laser pulses. The characteristic monoexponential relaxation time of the process was ~300 ps. The results obtained were analysed taking account of the special features of the splitting of the energy levels of tungsten ions with different degrees of oxidation and of delocalisation of the valence states within separate elements of the polytungstic acid structure.