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The influence of Mg and Ca atoms on the optical breakdown threshold of a nonlinear ZnGeP₂ crystal at a wavelength of 2.097 mm is studied. An impurity was introduced using diffusion doping; the material was sputtered onto a ZnGeP₂ substrate, followed by annealing in vacuum at a temperature of 750 °C for 200 hours. It is shown that the introduction of Mg into a single crystal increases the optical breakdown threshold by 31%. When ZnGeP₂ is doped with Ca atoms, the opposite trend is observed. It is suggested that due to the creation of additional channels for energy dissipation of radiative and fast non-radiative relaxation processes through impurity energy levels, the optical breakdown threshold changes, which requires experimental confirmation.

In coastal water bodies formed by separation from the White Sea during the post-glacial uplift of the coast, in the chemocline (the gradient zone between the aerobic and hydrogen sulfide zones), a colored layer of water with a development of phototrophic microorganisms is often observed. The solar light transmission spectra measured at different horizons under water in three stratified water bodies in the coastal marine area using a submersible fiber optic probe are compared with the absorption spectra of light by water from the same horizons. In the layers with massive development of anoxygenic phototrophs, the concentrations of bacteriochlorophylls were determined from the absorption spectra. According to the data obtained, the ranges of the transmitted solar spectrum in the water column (“color ecological niches”) are largely determined by humic substances dissolved in water. Their concentration increases as the water body is isolated from the sea, due to which the photic zone narrows with depth, the chemocline becomes closer to the surface, and a shift towards longer wavelengths appears in the spectrum of light entering the chemocline. In the marine bay, the 520- 600 nm part of the spectrum reaches the chemocline, in the marine stratified lagoon, wavelengths of 510-6700 nm predominate, in reservoirs with a fresh surface layer of water, the solar spectrum is shifted to the red region (520-7200 nm). It is shown that "color ecological niches" in various water bodies are occupied by organisms whose light-collecting antennas are adapted to absorb light quanta of the corresponding spectral range.

Due to the importance of using the structure function for problems of optical radiation propagation in a turbulent atmosphere, the task of determining this function from the known mode coefficients of wavefront expansion was set. New formulas have been derived for the exact analytical calculation of the wavefront phase structure function on a circular aperture. Unlike the previously published analytical method, the proposed approach correctly accounts the entire domain, including the area near the edge of the aperture. The new method is compared to the published one and a numerical calculation with the distretization chosen sufficiently fine. The test samples comprised Kolmogorov wavefronts and Zernike polynomials and Karhunen-Loѐve functions corresponding to the Kolmogorov turbulence model. The deviations of the results of the published before method from the new one and from the numerical calculation are provided. The advantages and generality of the new method are stated and explained. The result will make it possible to accurately determine the structure function of the wavefront by its mode coefficients in problems of optical radiation propagation in randomly inhomogeneous media.

Micropowders made of transparent semiconductor and dielectric materials (ZnSe, MgF₂, CaF₂, SiO₂, BaF₂, MgAl₂O₄, Al₂O₃, Nd:Y₂O₃, YSZ, and TiO₂) are theoretically studied. The refractive indices of these materials are in the range 1.38 ¸ 2.48. As a result of calculations, it is found that the combination of scattering and interference of radiation increases its intensity by one or two orders of magnitude compared to the intensity of the incident radiation in a medium of particles several microns diameter. It is shown that this enhancement increases with the refractive index of the particle material. In our opinion, both nonlinear mechanisms of laser radiation absorption and avalanche ionization lead to an increase in the electron concentration in such local maxima. As a result, the material begins to heat up to the point of ablation.

The paper presents the results of numerical simulation of one of the least studied excimer lasers, a KrCl molecule laser. The simulation was carried out in a 1D approximation, where laser radiation were calculated along the optical axis between plane-parallel mirrors, and the system of kinetic equations and the Boltzmann equation were solved in each transverse layer of the active medium. The theoretical data well agree with the results for the EL series KrCl laser (HCEI SB RAS). The effect of the excitation discharge width on the energy characteristics of the laser is numerically shown. The suggested model and the obtained estimates can be used as tools for optimizing initial parameters when developing more powerful laser systems.

IR lasers are widely used in various fields of science and technology. In this regard, expanding the spectral range and obtaining effective generation in the IR is an urgent task. The object of our study is a laser based on the self-terminating transition of Eu atom with a radiation wavelength of 1.76 mm. In this work, we investigated the possibility of increasing the output parameters of such a laser by increasing the length of the active zone of the gas discharge tube (GDT). It is shown that increasing the volume of the discharge tube from 157 to 314 cm³ while maintaining the pump power level at 1200 W makes it possible to double the output power and laser efficiency. For the first time, an average radiation power of 2.5 W was achieved at the 1.76 mm line. The maximal efficiency of 0.3% is achieved at a pump power of 500 W. After 100 hours of operation, the energy characteristics of the Eu+Ne laser with an active zone volume of 314 cm³ demonstrated good repeatability, which allows us to conclude that it is possible to further increase the energy characteristics and lifetime of this laser. The results of the work can be used in microprocessing of materials, as well as in active optical systems associated with the visualization of fast processes.

The location of the electrodes of a copper vapor laser (CVL) discharge tube in cold buffer zones, where there are no metal vapors, leads to the formation of a phantom current before the “breakdown”. This necessitates the evaluation of whether the phantom current is an additional factor limiting the energy characteristics and what is the mechanism of this limitation? It is shown that at the initial stage of pumping, the intrinsic capacitance of the discharge tube is charged up to the “breakdown”, which determines two processes during this period of time - the population of metastable states of copper and the generation of a phantom current, which occurs as a result of shunting of the intrinsic capacitance of the discharge tube by the cold buffer zone from the anode side of the discharge tube. The mechanism of phantom current generation and its role in limiting the energy characteristics of CVL are considered. The studies indicate two problems on the way to improve the energy characteristics of CVL and the direction of search for their solution: the first is high pre-pulse concentration of electrons in the active medium and the second is the generation of a phantom current caused by processes in the cold buffer zones.

The results of the study of two permafrost-hilly swamp complexes located in the valley of the Chernaya River, the right-bank tributary of the Yenisei River (near the city of Igarka), are presented. Among them are coarse-tuberous and flat-tuberous peatlands of different ages, genesis and stages of development. The modern vegetation cover of the complexes is characterized, a detailed morphostructural description of peat profiles is given, a botanical analysis is performed and the values of the degree of decomposition, ash content and moisture content of peat are determined. The thickness of the coarse-tuberous peat bog deposit is 4.0 m, the approximate age is 8 thousand years ago. In the process of its formation, it underwent six stages of change, of which the first was forest. The peat deposit is classified as forest-swamp and marsh subtypes. The main peat-forming agents from bottom to top of the profile were successively eutrophic hypnosis mosses, mosses ( Hypnales W. R. Buck et Vitt), sedges ( Carex L.), horsetails ( Equisetum L.) and, finally, oligotrophic sphagnum mosses ( Sphagnopsida Ochyra). The flat-tuberous peat bog with a capacity of 1.3 m and an age of about 3 thousand years in its development has gone through two stages of vegetation changes, of which the first is forest. Peat deposit of forest-marsh and marsh subtypes. Throughout its depth, ice layers are recorded. In the lower part of the peat profile, the main peat-forming agents were eutrophic hypnomic mosses, and in the upper part - oligotrophic sphagnum mosses. Changes in the vegetation cover of hilly peatlands occurred both as a result of changes in the regional climate in the Holocene, and due to the appearance of permanent permafrost in peatlands, heaving of mounds and their subsequent thawing. The appearance of spots of exposed peat on the day surface of peatlands and the formation of a powerful lichen cover in their place indicate the cessation of the peat formation process.

We studied poorly drained sedge-sphagnum pine forests ( Pinus sylvetris L.) in the southern taiga subzone of Western Siberia, drained by a network of open shallow channels 25 years ago at the time of the study (geographical coordinates 56°23′71″ N, 84°34′04″ E). The depth of standing swamp waters for three years of research averaged 23.2 ± 9.9 cm during the warm period. Soils - cultivated transitional (mesotrophic) type on powerful sedge-sphagnum peats. They are characterized by an acidic environment reaction - pH 4.0, a loose composition density of 0.10 g/cm³ and an ash content of 8.9-5.2%, decreasing with depth. The soil profile in the warm period is poorly differentiated into a zone of intense oxidative processes (0-10 cm) - 570-660 mV (median 610) and moderately oxidative (10-30 cm) - 430-640 mV (median 590). The main direction (trend) of seasonal fluctuations of the redox potential (RP) is characterized by an average weekly acceleration of 7.2 mV with an average weekly deceleration of 0.23 mV from June to October. RP by the type of linear function is significantly associated: positively with the groundwater level ( R ² = 0.65) and soil temperature ( R ² = 0.56), negatively with volumetric humidity ( R ² = 0.60). A significant second-order parabola-type relationship of RP was revealed: negative - with Fe²⁺ ( R ² = 0.48) and ammonium ( R ² = 0.57), positive with Fe³⁺ ( R ² = 0.39), multidirectional - with Fe_C ( R ² = 0.55) and water-soluble organic carbon ( R ² = 0.54). By the method of canonical analysis, it was found that the RP is determined by a set of hydrothermal indicators by 81 %. The volume humidity contributes the greatest weight to the conditioned effect. Various forms of iron cumulatively estimate the development of RP-reactions by 52 %, the dominant contribution belongs to Fe²⁺. The set of carbon and NH⁴⁺ determines the redox potential by 61 % with the largest weight of carbon in the set of characteristics.

It is accepted that the amount of damage is equal to the difference in the value of the stands before and after the external impact. Hence, the task of determining damage comes down to identifying the cost of the stands. It is shown that the cost can be represented as the sum of the ecosystem (ecological and resource) functions of the stands. The calculation is performed relative to a specific function, the cost of which is known. As such a function, a wood resource was used, which, in the form of a tax rate of payment, is balanced by location, tree species, marketability classes and is widely used as a standard indicator in setting fees for forest use. The sequence of damage calculations is demonstrated using the example of the southern taiga forests of the Yenisei, Nizhne-Yenisei, and North Yenisei forest districts of Krasnoyarsk Krai. There was an outbreak of Siberian silkworm ( Dendrolimus sibiricus Tschetverikov) here between 2016 and 2018. The area with varying degrees of damage to stands amounted to 803,983 hectares. The total area of forest inventory units where tree stand death was recorded is 2,034,665 hectares. To calculate the damage, mass forest survey materials were used as initial data. Descriptions of forest inventory units were analyzed separately for protective, operational and reserve forests. Calculations were made based on the predominant tree species. The cost of protective forests turned out to be more than operational ones, and the cost of ecosystem functions of the stands turned out to be an order of magnitude higher than the tax value of the wood resource. The total cost of stands before the Siberian silkworm outbreak was determined to be 70,275.2 million rubles, after the outbreak - 52,249.8 million rubles. The total damage to forests amounted to 18,025.5 million rubles - 25.7 % of the cost of stands before the Siberian silkworm outbreak.