A.V. Klimkin1, M.E. Levitskii1,2, M.V. Trigub1
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Keywords: International Conference, pulsed laser, laser application, laser physics, laser chemistry, laser material, laser source, excilamp
From September 12 to 17, 2021, the 15th International Conference on Pulsed Lasers and Laser Applications AMPL-2021 was held in Tomsk at the Institute of Atmospheric Optics, Siberian Branch, Russian Academy of Sciences . The topics traditionally reflected the results of research over the past few years: fundamental issues of laser physics, processes in laser active media, gaseous active media, new lasers and laser systems, laser applications, creation of devices based on laser sources, and new optical technologies.
Results of the study of features of the spectral, temporal, and spatial characteristics of the radiation from neutral neon atoms pumped by an inductive pulsed cylindrical discharge are presented. Lasing was obtained at wavelengths of 540.1 and 614.3 nm with optical pulse duration at levels of 13 ± 1 and 5 ± 1 ns (FWHM), respectively. The cross section of the laser radiation had the shape of a ring with a diameter of 33.1 ± 0.1 mm and a width of 5.6 ± 0.1 mm. The intensity distribution of the lasing ring was nonuniform and has a grain structure, typical of lasers operating in the amplified spontaneous emission mode. The grain region is inhomogeneous in form and size and shows a pronounced radial symmetry, which, according to our assumption, is due to the nature of the electric field in an inductive cylindrical discharge.
D.V. Shiyanov, V.A. Dimaki, M.V. Trigub, V.O. Troitskii, P.I. Gembukh
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: CuBr laser, energy input, cable pulse autotransformer, peaking capacitor, excitation pulse duration
A possibility of increasing the radiation power of a CuBr laser by increasing the pumping energy is studied. For this purpose, a three-cascade system of nanosecond oscillators is used, which excite the active medium of the laser when connected in series. Each source provides a pump power of up to 2 kW. A TGI1-1000/25 thyratron is used as a switch. The pump sources perform pulse charging of the working capacitance, which ensures stable operation of the system. The use of such a power source for excitation of a gas-discharge tube 5 cm diameter and 90 cm long provides for an output power of more than 40 W in a modified scheme with pulse cable autotransformer and peaking capacitor. Tests of the source confirm its effectiveness for pumping high power metal vapor lasers.
V.O. Troitskii
V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: significantly nonlinear second harmonic generation mode, solution to a set of nonlinear equations, preset field approximation, optimization of focusing and wave detuning parameters
The process of second harmonic generation (SHG) of laser radiation in a BBO crystal is theoretically studied with the aim of determining optimal values of focusing and wave detuning parameters providing maximal SHG efficiency. This optimization problem is solved under an additional condition, that is, the maximal radiation power density should not exceed an a priori specified value. No restrictions are posed on the radiation power. The study consists of two parts. This is the second part of the work, where the influence of the additional condition on the process and results of solution of the optimization problem is studied using rigorous methods for solution of a system of nonlinear wave equations. The main results of the studies are the dependences of the maximum attainable SHG efficiency on the laser radiation power. It is shown that the optimal values of focusing and wave detuning parameters can be found with the use of the preset field approximation, which significantly reduces the amount of calculations, in many practical cases.
V.F. Tarasenko, E.Kh. Baksht, A.G. Burachenko, N.P. Vinogradov
High Current Electronics Institute of the Siberian Branch of the RAS, Tomsk, Russia
Keywords: mini jets, diffuse discharge, atmospheric discharges, red sprites, blue jets
The effect of the electrode material (aluminum and stainless steel) on the generation of mini-jets on the color of a pulse-periodic diffuse discharge in air, nitrogen, and argon is studied. A discharge was generated under generation of runaway electrons in an inhomogeneous electric field. It is found that the material of the electrodes significantly influences the color of the mini jets that originate when bright spots appear on the electrodes. It is confirmed that the use of aluminum electrodes colors the mini jets red, and of iron electrodes, blue. It is shown that the color of the discharge plasma in the mini jet region corresponds to the color of high-altitude atmospheric discharges (red sprites and blue jets) and differs from the color of diffuse discharges in air and nitrogen under the same pressure.
T.A. Sokolova
Southern Scientific Center RAS, Rostov-on-Don, Russia
Keywords: oak forests of the steppe basin of the Don River, syntaxonomy, union Aceri campestris-Quercion roboris
The paper presents the results of long-term studies of the vegetation of bayrachny oak forests in the south of the European part of Russia (Volgograd, Voronezh, Rostov regions). Based on a large amount of factual material (more than 1150 geobotanical descriptions, including 777 descriptions by G.M. Zozulin), a floristic classification of mesophytic oak forest communities in the region, which are attributed to the alliance Aceri campestris-Quercion roboris Bulokhov et Solomeshch in Bulokhov et Semenishchenkov 2015, was carried out using the Braun-Blanquet method (1964). For a long time, the forests of the south of the European part of the country, due to little study, belonged to the alliance Aceri tatarici-Quercion Zólyomy 1957. New data (Goncharenko et al., 2020; Sokolova, Ermolaeva, 2021) made it possible to clarify their position in the classification system of forest vegetation in Russia. A new association was installed Ulmo minoris-Fraxinetum excelsioris ass. nov. hoc loco and the new suballiance Ulmo minoris-Fraxinenion excelsioris suball. nov. hoc loco in the alliance Aceri campestris-Quercion roboris. The new syntaxons are transitional forest communities with features of the Carpino-Fagetea Jakucs ex Passarge 1968 and Quercetea pubescentis Doing-Kraft ex Scamoni et Passarge 1959 classes. Their distinctive feature is the presence of both non-moral phagetals: Adoxa moschatellina, Aegopodium podagraria, Asarum europaeum, Campanula trachelium, Corylus avellana, Lathyrus vernus, Milium effusum, Pulmonaria obscura, Viola mirabilis, etc., and species with circumpontic distribution: Arum elongatum, Dentaria quinquefolia, Laser trilobum, Lysimachia verticillaris, Physospermum cornubiense, Scilla sibirica, Symphytum tauricum, Veronica umbrosa, Vincetoxicum scandens, which are characteristic of the recently isolated alliance Scutellario altissimae-Quercion roboris Goncharenko et al. 2020, which unites the subxerophilic oak forests of Ukraine and southern Russia, found in the steppe zone and the southern part of the forest-steppe zone. The ideas about the area of the alliance Aceri campestris-Quercion roboris, which has expanded beyond the forest-steppe zone to the central regions of the Rostov region, have been expanded.
I.B. Kucherov1, L.A. Novikova2, S.A. Senator3 1V.L. Komarov Botanical Institute RAS, St. Petersburg, Russia 2Penza State University, Penza, Russia 3N.V. Tsitsin Central Botanical Garden RAS, Moscow, Russia
Keywords: multizonal species, meadows, dry grasslands, meadow steppes, latitudinal zonation, European Russia
As follows from the analysis of relevés collected in the 13 key areas in European Russia (see Table 1, Fig. 1), phytocoenotic behavior of many multizonal meadow species of vascular plants changes notably when passing from the boreal- and then the nemoral-forest zones to the subzone of meadow steppes. The constancy and cover of the 17 model species, distributed along the latitudinal zones and subzones and then the dry grassland, meadow, and steppe vegetation types (see Table 2), is influenced by warmth supply and climate continentality factors together with those of location within a particular river basin and regional specifics of the Quaternary history. Zonal trends of cover changes for Stellaria graminea and Bromopsis inermis in the series from dry boreal grasslands to steppes or from northern to southern Calamagrostis epigeios-dominated meadows, respectively, are proved by the Spearman rank correlations between the mean cover and the growing degree-days above 10 C or the Konrad continentality index (see Table 3). Xerophytization of many species, mesic in the boreal-forest zone, is observed under the steppe conditions, the process which often results in the separation of new micro-species. The anemochorous meadow plants were subject to dispersal mainly along the watersheds but the barochors were dispersed mainly by water flow or in both ways in the course of the formation of meadow-steppe coenofloras in the Late Pleistocene and the Holocene. Both redwood-dry-grassland and floodplain-meadow coenofloras influence the steppe set of meadow species, and the latter can be grouped into the three ecological-historical “corteges” of vegetation, namely the watershed, the floodplain, and the combined ones.
We studied the seed set of the andromonoecious Chaerophyllum aromaticum (Broadleaf chervil), a perennial or biennial polycarpic herbaceous plant. Our survey was carried out in natural conditions of the Moscow region from 2018 to 2021 according to generally accepted methods of studying plant seed sets. We showed that the seed set of individuals depends on the degree of synflorescences branching. Broadleaf chervil has three types of individuals with double umbels on shoots of I-II, I-III, and I-IV orders. C. aromaticum has a high potential (number of ovules per individuals) and real (number of seeds per individuals) seed set (up to 3500 seeds per individual) and the proportion of perfect flowers forming full seeds (92-93 % per individual). The potential and real seed set of terminal double umbels is higher than that of individual double umbels on shoots of the following orders in individuals with the least and most branched synflorescences. In individuals with double umbels on shoots of I-III orders, the number of ovules and seeds in double umbels on shoots of II order is higher than in terminal double umbels. In Broadleaf chervil, the seed set of double umbels on shoots of the same branching order naturally increases with an increase in the branching of the shoot system. The contribution of the seed set of double umbels to the total seed set of C. aromaticum individuals also depends on the degree of synflorescences branching. With an increase in the branching of the shoot system, the share of seed set of terminal double umbels and double umbels on second-order shoots gradually decreases. These characteristics of double umbels on third-order shoots naturally increase due to both their numerical predominance and, in some cases, a greater number of ovules and seeds formed by them. A high seed set ensures successful seed reproduction of Broadleaf chervil in natural conditions.
Y. V. Naumenko1, Ch.D. Nazyn2 1Central Siberian Botanical Garden of the Siberian Branch of the Russian Academy of Sciences, Novosibirsk, Russia 2Tuvan State University, Kyzyl, Russia
Keywords: Algae, taxonomic composition, Cyanoprokaryota, Bacillariophyta, Republic of Tyva
For the first time, information is provided about the Ceiba River and its tributary Khon, which carry their waters in the state nature reserve of republican significance “Khutinsky”, located in the spurs of the southern macro slope of the Western Sayan. A list of algae is given, including 89 species and intraspecific taxa, which belong to 51 genera, 28 families, 8 classes and 4 divisions. It has been established that the basis of algoflora consists of diatoms and blue-green algae. Common dominants have been identified for two rivers: Meridion circulare and Diatoma mesodon, D. hiemale and Didymosphenia geminata. An ecological and geographical analysis was carried out, according to which algoflora is represented by benthic species, with a predominance of indifferent forms in relation to halobicity and active reaction of the environment. 72 types of water saprobity indicators were identified in the studied watercourses. The predominance of betamesosaprobionts and oligosaprobionts was noted. Cosmopolitans and Boreal species dominated geographically.
