Application of ion implantation for synthesis of copper nanoparticles in a zinc oxide matrix for obtaining new nonlinear optical materials

We have obtained a layered composite material by implantation of single crystal zinc oxide (ZnO) substrates with 160-keV Cu⁺ ions to a dose of 10¹⁶ or 10¹⁷ cm⁻². The composite was studied by linear optical absorption spectroscopy; the nonlinear optical characteristics were determined by means of Z-scanning at a laser radiation wavelength of 532 nm. The appearance of the optical plasmon resonance bands in the spectra indicated that ion implantation to the higher dose provides for the formation of copper nanoparticles in a subsurface layer of ZnO. The new nonlinear optical material comprising metal nanoparticles in a ZnO matrix exhibits the phenomenon of self-defocusing and possesses a high nonlinear absorption coefficient (β=2.07×10⁻³ cm/W).     

Refinement of tungsten microstructure upon severe plastic deformation

The effect of equal-channel angular pressing and high-pressure torsion on the formation of an ultrafine-grained structure in commercially pure tungsten has been studied. The structure was tested by the methods of transmission and scanning electron microscopy using electron backscatter diffraction analysis. The material microhardness depending on the stored deformation has been evaluated. In the samples subjected to severe plastic deformation, the quantitative structure characteristics (the average size of grains/subgrains and misorientation-angle distribution) have been determined.     

Microstructure and crystallographic texture of titanium subjected to combined severe plastic deformation processing

Structural studies of the nanocrystalline titanium powders produced by cryogenic milling followed by severe plastic deformation consolidation are performed. The results obtained are compared with the results obtained for monolithic titanium subjected to severe plastic deformation by torsion.     

Development and applications of a compact hybrid tabletop terawatt chirped-pulse amplification Ti:sapphire-Nd:glass laser for x-ray lasing and harmonic generation

A hybrid tabletop (2 m x 3 m) terawatt chirped-pulse amplification Ti:sapphire-Nd:glass laser (1054 nm, 475 fs, 500 mJ, 9 x 10(17) W cm(-2)) has been developed for laser-matter experiments. An overall gain factor of 10(10) was achieved for the laser. The results of laser applications in the studies of soft-x-ray Ni-like Mo 18.9-nm lasing and of harmonic generation from solid surfaces are presented.     

Structural, optical, and nonlinear optical absorption/refraction studies of the manganese nanoparticles prepared by laser ablation in ethanol

The structural, optical, and nonlinear optical properties of the manganese nanoparticles prepared by laser ablation in various liquids were investigated using the 532 and 1064 nm, 50 ps laser pulses. The TEM and spectral measurements showed temporal dynamics of size distribution of Mn nanoparticles in solutions. The nonlinear absorption (β = 2 × 10⁻¹⁰ and 4 × 10⁻¹¹ cm W⁻¹) and positive nonlinear refraction (γ = 8 × 10⁻¹⁵ and 2 × 10⁻¹⁴ cm² W⁻¹) of picosecond radiation were observed in the Mn colloidal suspensions using the 1064 and 532 nm radiation, respectively     

33rd harmonic generation from aluminium plasma

We report the high-order harmonic generation of up to the 33rd harmonic (λ?=?24.1 nm) of Ti?:?sapphire laser radiation from the prepulse-produced aluminium plasma. The plateau pattern for high harmonics was observed, contrary to the steep decrease in harmonic output appearing in the case of carbon plasma under analogous conditions. The harmonic generation appeared to be efficient in the case of singly ionized Al plasma when the high-charged ion concentration was negligible. The conversion efficiency for the 25th harmonic was measured to be 2× 10^?6, which was twenty times higher when comparing to the case for boron plasma. The comparison of the harmonics generating from the Al and Al₂ O₃ plumes showed equal conversion efficiencies and cutoff harmonics.     

Pulsed nuclear power stations as the basis of the global power industry: Resource and ecological considerations

VNIITF. Translated from Atomnaya énergiya, Vol. 78, No. 6, pp. 359–364, June, 1995.     

Dynamics of the laminar flame front of a homogeneous propane-air mixture with a pulsed-periodic action of an electric field

Results of an experimental study of the flame-front dynamics in a homogeneous propane-air mixture under a pulsed action of an electric field are presented. Front surface areas turned to different-pole electrodes are found to move with different velocities. The effects observed can be explained by the hydrodynamic action of the ion wind.     

Laser third harmonic generation in organic dye vapors

The phenomenon of nonlinear optical conversion of a YAG:Nd laser radiation frequency from IR to UV spectral range in naphthalene vapors was studied. The optimum temperature of naphthalene vapors (170°C) was found at which the pumping radiation is synchronously converted into the third harmonic emission. A mechanism of the third harmonic generation is proposed based on the difference frequency generation in a six-photon process. The efficiency of conversion to the third harmonic generation varied within 10⁻¹⁰–10⁻⁸, depending on the pumping intensity and cell temperature. Nonlinear optical characteristics of naphthalene vapors were calculated for the generation using nonlinearities of the third and fifth order.     

Superstrength of nanostructured metals and alloys produced by severe plastic deformation

Metals and alloys produced by severe plastic deformation (SPD) are characterized by not only an ultrafine grain size, but also other structural features, such as nonequilibrium grain boundaries, nanotwins, grain-boundary segregations, and nanoparticles. The present work deals with the study of the effect of these features on the strength of SPD metals and alloys. In particular, it has been shown that, with segregations on grain boundaries and nonequilibrium boundaries, the yield stress of the material can exceed considerably the values extrapolated to the range of ultrafine grains using the Hall-Petch relationship.