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Belevtsev A.A.,RAS Institute for High Energy Densities | Kazantsev S.Yu.,RAS A.M. Prokhorov General Physics Institute | Kononov I.G.,RAS A.M. Prokhorov General Physics Institute | Firsov K.N.,RAS A.M. Prokhorov General Physics Institute
Quantum Electronics | Year: 2010

The development of detachment instability in active media of electric-discharge non-chain HF(DF) lasers due to the electron-impact detachment of electrons from negative ions is considered. This instability is initiated in large volumes of SF6-based gas mixtures, spatially separated from electrodes and heated by a pulsed CO2 laser. The self-organisation of self-sustained volume discharge upon laser heating, which results in the formation of quasi-periodic plasma structures within the discharge gap, is experimentally investigated. The evolution of these structures, depending on the gas temperature and specific deposition of electric energy, is analysed. The possible relationship between the self-organisation and detachment instability is discussed. A mechanism of development of single plasma channels in the working media of HF(DF) lasers, based on electron-impact destruction of negative ions is proposed. © 2010 Kvantovaya Elektronika and Turpion Ltd.

Veysman M.,RAS Institute for High Energy Densities | Andreev N.E.,Moscow Institute of Physics and Technology | Cassou K.,University Paris - Sud | Cassou K.,French National Center for Scientific Research | And 6 more authors.
Journal of the Optical Society of America B: Optical Physics | Year: 2010

A non-symmetrical theoretical model is used to describe the propagation of laser beams in dielectric capillary waveguides under non-ideal coupling conditions. The displacement of the laser beam focusing point from the capillary axis, the deviation of the transverse energy distribution from a symmetric one, and an angle of incidence different from zero modify, through the excitation and beating of several modes, the energy repartition during the propagation in the waveguides. The results of modeling are in very good agreement with experimental results, obtained with a low-intensity laser beam on a test bench, where good control of the laser energy distribution in the focal plane, the focusing point position, and the angle of incidence was achieved. © 2010 Optical Society of America.

Dzlieva E.S.,Saint Petersburg State University | Karasev V.Yu.,Saint Petersburg State University | Petrov O.F.,RAS Institute for High Energy Densities
Journal of Experimental and Theoretical Physics | Year: 2012

The rotational dynamics of single dust grains in a weak magnetic field is investigated on a kinetic level. Experiments reveal spin-up of spherical dust grains and alignment of their magnetic moments parallel to the magnetic induction vector. The angular velocity of spinning prolate grains varies as magnetic induction increases to 250 G. Spinning dust grains are found to flip over only when the magnetic field magnitude is changing. The results demonstrate that dusty plasma has paramagnetic properties. Qualitative interpretations are proposed to explain newly discovered phenomena. © Pleiades Publishing, Inc., 2012.

Simonenko E.P.,RAS Kurnakov Institute of General and Inorganic Chemistry | Ignatov N.A.,RAS Kurnakov Institute of General and Inorganic Chemistry | Simonenko N.P.,RAS Kurnakov Institute of General and Inorganic Chemistry | Ezhov Yu.S.,RAS Institute for High Energy Densities | And 2 more authors.
Russian Journal of Inorganic Chemistry | Year: 2011

Nanocrystalline powders of super-refractory complex carbides Ta 4HfC 5 and Ta 4ZrC 5 were synthesized using a hybrid method comprising sol-gel technology for preparing highly dispersed metal oxidescarbon starting mixtures and a relatively low-temperature (1300-1500°C) carbothermal synthesis under a dynamic vacuum (P = 1 × 10 -3 to 1 × 10 -5 MPa). The elemental and phase compositions of the products and average crystallite sizes were determined. TEM was used to study particle morphology and dispersion. Microstructures were observed by SEM. BET specific surface areas were determined for powders prepared at 1400°C. © 2011 Pleiades Publishing, Ltd.

Veysman M.,RAS Institute for High Energy Densities | Andreev N.E.,Moscow Institute of Physics and Technology | Maynard G.,University Paris - Sud | Cros B.,University Paris - Sud
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2012

A model describing the nonsymmetrical laser-pulse propagation in capillary tubes with inner radius smoothly varying with the capillary length is proposed. Using this model, the use of capillaries with specially profiled entrance sections (particularly cone matching elements) for improving the coupling of the laser energy into a capillary and avoiding capillary ablation is analyzed. It is shown that cone entrances with a sufficiently small angle (αcone≠10 mrad) help decrease the longitudinal energy flux and ablation of the entrance face of a capillary, but do not remove the requirements on the precision of laser-pulse focusing necessary to obtain regular laser fields, characterized by a symmetrical intensity distribution, centered on the capillary axis. To achieve regular laser fields without strong transverse gradients, the angle between the laser and capillary axes has to be smaller than 1 mrad for capillaries with an inner radius of the order of tens of microns. © 2012 American Physical Society.

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