G. K. Vasiliev

Multifrequency sounding with DF laser-based lidar system: preliminary results

Performance capabilities of the developed multifrequency lidar system based on the pulsed chain chemical DF laser are presented in the paper. The purpose of the research and development is the creation of a lidar for the detection and recognition of aerosol impurities in the atmosphere, and the main attention is paid to realization of these resources of the system. Based on the numerical modeling data, the restrictions to the statement of the recognition problem are formulated. It is shown that the lidar performance characteristics allow to detect and to recognize aerosol impurities in the atmosphere for distances of up to 10 - 15 km.

Recognition of composition and of microphysical characteristics of aerosol clouds in multifrequency sounding

The recognition of composition and of microphysical characteristics of aerosol impurities is one of the most urgent tasks in monitoring of atmosphere. Some approaches to its solution are considered in the work. At first stage we were limited to five substances: fine-dispersion water and dust as background aerosol components of atmosphere; coarse- dispersion tributilamin, turbine oil and petroleum as possible impurities. Tributilamin was chosen as spectral analog of V gases. The modeling of input spectra and the recognition were carried out on 12 discrete lines in 2.9 - 4 micrometers spectral rage. As is well known, in this range the considered impurities have the pronounced spectral dependences of aerosol backscattering, the so-called spectral resonances. Spectra of aerosol backscattering for these substances were calculated with Mie theory. We applied evolutionary algorithm (genetic algorithm) and also more traditional optimization methods, namely gradient descent method, for recognition procedure. The comparative analysis of the mentioned methods was done; the concrete results of recognition and the dependence of recognition efficiency on the number of wavelength channels and on the accuracy of spectrum recording are given.

Recognition of composition and of microphysical characteristics of aerosol clouds in multifrequency sounding with DF laser-based lidar system

One of the most actual problems in monitoring of the atmosphere is the recognition of chemical composition and microphysical characteristics of atmospheric aerosol impurities. In the present work the opportunities of lidar system based on multifrequency pulsed chain chemical DF laser (λ = 3.6 - 4.2 μm) are considered from this point of view. With the purpose of working-out of the requirements to the primary performances of lidar system, model experiments are executed as to the problem of recognition of aerosol impurities in the atmosphere with the use of DF-laser radiation lines. The obtained results and their analysis are presented in the paper.

Superpowerful lasers on chain chemical reactions for studying dense relativistic plasma and laser fusion

The expected energetic performances are presented for amplification of short pulses (approximately 10-12 s) either directly in chain pulsed chemical laser (PCL) active medium, or in active media created by optical pumping of resonantly absorbing molecules by radiation of PCL. The calculations were based on the data for PCL energetic and amplifying performances and also on the data for pumping of N2O molecules by HF laser radiation, both being obtained by us earlier. For amplifying a short pulse in DF-CO2 PCL active medium, the energy output of 6J/l is achievable, while 8 - 10 J/l is attainable for regenerative amplification in HF(DF) laser (50 J/l(DOT)atm - under free oscillation conditions for both). For regime of optical pumping, the energy of N2O short-pulse radiation can make 10% of pump (PCL output) energy. A series of other promising three- and four-atomic molecules is considered. The comparison of various variants of embodying of superpowerful laser systems based of chain chemical lasers is carried out. The conception of construction of short- pulsed laser systems with radiation energy of up to 104 J is submitted with the expectation of their using for creation of dense relativistic plasma, as new perspective object of researches, and for realization of laser fusion.

Design and performance of a Petawatt subpicosecond N2O‐laser pumped by HF — chemical laser radiation

Progress on developing a petawatt laser source in 10μm region is described. Analysis of optical pumping N2O containing active media by pulsed multifrequency HF laser has been performed. It is shown that amplification of ultrashort pulses should be carried out in the gain band centered at 930cm−1. Amplification of seed ultrashort (∼1ps) pulses in atmospheric and high pressure N2O (up to 5atm) amplifiers pumped by powerful pulsed HF chemical lasers is theoretically studied. It is shown that N2O atmospheric pressure amplifiers can be effectively used for production output energy of 1kJ.

Optical pumping of the N{sub 2}O-He and N{sub 2}O-CO{sub 2}-He mixtures by a pulsed multifrequency HF laser for producing active media to amplify 10-{mu}m high-power ultrashort pulses

Optical pumping of the N2O—He and N2O—CO2—He active media (at a total pressure of 1 atm) by ~1-μs pulses from a multifrequency HF laser is studied with a view to use these media for amplifying a 10-μm, 10-12-s ultrashort pulse (USP). Transitions forming the USP amplification band are determined, the energy stored in them is found, and the gains corresponding to maximum inversion in the medium are calculated.