Medvedev A.E.,RAS Institute of Laser Physics
Russian Physics Journal | Year: 2012
A transport equation has been derived for a plasma treated as a continuous medium. In contrast to the well-known magnetohydrodynamic approach, in deriving the equation, the spatial charge density was taken into account which has made it possible to determine the self electric field of the plasma and the consistent motion of charged particles of different charge sign. Analysis of the equation terms that describe the contributions of various types of energy to the plasma transport has been performed. In the limit of dominant thermal energy, the criteria for plasma quasineutrality and ideality transforms into the well-known criterion defined by the squared ratio of the Debye radius to the characteristic size, and plasma transport is reduced to ambipolar diffusion. Based on the equation obtained, models of moderate-pressure and atmospheric-pressure glow discharges can be considered to interpret experiments with fields too low to provide ionization, so that a bulk plasma is sustained by charge carriers coming from near-electrode regions, and the cross-section of the current filament is determined by the balance of forces that represent the action of the thermal energy and of the energy of electrical interaction between the plasma particles. © 2012 Springer Science+Business Media, Inc.
Bagayev S.N.,Novosibirsk State University |
Leshchenko V.E.,RAS Institute of Laser Physics |
Trunov V.I.,Novosibirsk State University |
Pestryakov E.V.,Novosibirsk State University |
Frolov S.A.,RAS Institute of Laser Physics
Optics Letters | Year: 2014
We report on the first experimental realization of coherent combining of parametrically amplified femtosecond pulses. The proposed and implemented two-loop active stabilization system allows us to achieve 110 as relative timing jitter between combined pulses, which is necessary for efficient coherent beam combining. In each channel of the two-channel laser setup, pulses were parametrically amplified in β-BaB2O4 (BBO) crystals to 50 μJ energy, compressed to 49 fs duration, and then coherently combined with efficiency as high as 97%. Currently, it is the shortest duration of amplified pulses for which coherent combining is demonstrated. © 2014 Optical Society of America.
Boichenko S.,RAS Institute of Laser Physics |
Konig K.,Irkutsk State University
Journal of the Optical Society of America B: Optical Physics | Year: 2015
We theoretically demonstrate a technique allowing a highly efficient observation of all single-molecule emitters in one fluorescent image, regardless of the orientations of their transition dipole moments. To perform this technique, we combine near-unity collection efficiency for an arbitrarily oriented emitter and the elimination of the excitation efficiency dependence on the emitter's orientation. The former task is solved by placing the emitter in a special metallo-dielectric antenna [Opt. Lett. 36, 3545 (2011)]; the latter, by means of laser-scanning confocal fluorescence microscopy using elliptically polarized cylindrical vector beams [J. Exp. Theor. Phys. Lett. 97, 52 (2013)]. We present conditions under which the collection efficiency for arbitrarily oriented emitters is <98% and the excitation efficiency of an emitter of minimally excitable orientation amounts to >92% of the excitation efficiency of an emitter of maximally excitable orientation. These conditions are satisfied in the broad spectral range between 0.4 and 1.0 μm: the emitters can be excited with any wavelength and emit any fluorescence spectra in this range. The presented results are based on simulation data. © 2015 Optical Society of America.
Structure formation of atmospheric pressure discharge Topical Issue: Recent Breakthroughs in Microplasma Science and Technology Kurt Becker, Jose Lopez, David Staack, Klaus-Dieter Weltmann and Wei Dong Zhu
Medvedev A.E.,RAS Institute of Laser Physics
European Physical Journal D | Year: 2016
In this paper it is shown, by analyzing the results of experimental studies, that the outer boundary of the atmospheric pressure discharge pinch is determined by the condition of equality of plasma flows based on the thermal and electric field energy. In most cases, the number of charged particles coming from near-electrode zones is sufficient to compensate for losses in the discharge bulk. At large currents and enhanced heating, plasma is in the diffusion mode of losses, with recombination of charged particles at the pinch boundary. © 2016 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.
Fedorov V.I.,RAS Institute of Laser Physics
Proceedings - 2016 International Conference Laser Optics, LO 2016 | Year: 2016
The report emphasizes the importance of the study of terahertz radiation biological effects as another direction in the creation of diagnostic and therapeutic methods, along with terahertz imaging and terahertz spectroscopy. Therapeutic and diagnostic use of laser terahertz radiation based on the results of pre-conducted fundamental research of biological effects of terahertz radiation at the organismic, cellular and molecular levels presents. © 2016 IEEE.
Bryukvina L.,RAS Institute of Laser Physics
Journal of Luminescence | Year: 2015
Abstract The periodic filamentation patterns across and along laser channel tracks, induced by high-intensity femtosecond laser pulses in magnesium and sodium fluoride crystals, have been disclosed. The patterns are rationalized by deterministic vectorial effect, difference in propagations of linearly- and circularly-polarized laser pulses, and appearances of the orbital angular momentum of the light beams due to optical astigmatism. © 2015 Elsevier B.V. All rights reserved.
Kurbatov P.F.,RAS Institute of Laser Physics
AIP Advances | Year: 2011
A one-dimension model for positive-column plasma is analyzed. In the framework of this model, a complete, self-consistent set of equations for the plasma column is proposed and justified. Basic prerequisites for the model and the equations used in it are discussed at length to clarify the mathematics and physics that underlie the proposed generalized description of plasma states. A study of the equations has unveiled the existence of two structurally stable types of steady states and three integrals of motion in the plasma system. The first type of states corresponds to spatially homogeneous plasma, and the second type, to the self-forming plasma structure with striations. Analysis of spatio-temporal plasma structures (spatially homogeneous and stratified stationary plasma states) and their attendant phenomena is given in detail. It is shown that the equations offer a more penetrating insight into the physical states and properties of positive-column plasma in dc-driven gas discharges, and into the various phenomena proceeding in the discharge system. Such a behavior is intimately related to the influence which the electric field has on the rate of ionization reactions. The theoretical results are compared to experimental data and can be used for to place the great body of experimental data in their proper framework. The modern fluid bifurcation model proposed to describe the properties of non-isothermic positive-column plasma in dc-driven low-pressure noble-gas discharges proved to be rather realistic, capable of adequately reproducing the basic properties of real field-plasma systems. Copyright © 2011 Author(s).
Boichenko S.V.,RAS Institute of Laser Physics |
Martynovich E.F.,RAS Institute of Laser Physics
JETP Letters | Year: 2013
A polarization inhomogeneous vector beam, which is the complex superposition of radially and azimuthally polarized beams, has been studied computationally and theoretically in application to scanning fluorescence microscopy of single molecules. It has been shown that its application makes it possible to almost exclude the dependence of the intensity maximum of the scanning fluorescence image of a single molecule on its orientation. It has been demonstrated that the scanning of one horizontal plane of a solid matrix containing impurity luminescent molecules provides images of all molecules located in a 1-μm-thick layer, replacing three-dimensional scanning. Recommendations on the technical implementation of the proposed beam have been given. © 2013 Pleiades Publishing, Ltd.
Kurbatov P.F.,RAS Institute of Laser Physics
Physics of Plasmas | Year: 2013
A modern modification of the Schottky theory is proposed. It enables overcoming some of the difficulties and contradictions of the old theory and extends its capabilities in the analysis of radial distributions of ionized species. This allows us to consider the distributions of positive column plasma in noble gas d.c. discharges within a proper universal framework. The radial distributions of plasma species are basically similar in their nature and are independent of the character and features of plasma reactions. © 2013 American Institute of Physics.
Razhev A.M.,Novosibirsk State University |
Churkin D.S.,Novosibirsk State University |
Kargapol'Tsev E.S.,RAS Institute of Laser Physics
Laser Physics Letters | Year: 2013
For the first time, we have used a pulsed inductive discharge to initiate a chemical HF laser. This publication presents research into selection of an active medium for such a laser, as well as the composition of the gas mixture. For the mixture of H2-SF6 we have managed to obtain lasing in the infrared spectrum around 2.7 μm. Addition of buffer gases such as either He or Ne, or both of them, has resulted in increased lasing energy. Experiments have been performed to study the timing and output performance characteristics of the chemical HF laser at different pressure and pumping levels. For the mixture with Ne at a pressure of 45 Torr, the energy obtained was 10 mJ, and the peak pulse power -5 kW. The pulse duration (FWHM) was 2 μs. © 2013 Astro Ltd.