The results of lidar measurements of the vertical distribution of optical properties of dust aerosol from the Gobi and Taklamakan deserts in the free troposphere over Vladivostok are presented. A Mi-Raman lidar with a cross-polarization channel was used as an instrument, allowing for the retrieval of vertical profiles of a set of (3β + 2ε + δ) three backscattering coefficients (355, 532, 1064 nm), two extinction coefficients, and one depolarization coefficient at a wavelength of 532 nm. A high depolarization coefficient value (δ = 0.13–0.15), characteristic of submicrometer-sized dust aerosol particles, was observed in the altitude range of 3.00–4.25 km for the dust aerosol from the Gobi Desert. For the aerosol recorded from the Taklamakan Desert, this value was δ = 0.14 in the altitude range of 5–10 km. To obtain information on the spatial distribution of microphysical characteristics, an inversion procedure (3β + 2ε + δ) based on the model of randomly oriented spheroids was used. The complex refractive index within the dust layer had values typical for dust particles, with mr = 1.48–1.56 and mi = 0.001 for the aerosol from the Gobi Desert, and mr = 1.51–1.61 for the aerosol from the Taklamakan Desert.

One of the conditions of safe operation for the experimental tokamak reactor ITER is the possibility of mitigating disruption instability by massive injection of inert gases, in particular, of argon and neon. Here we present the results of assessing the influence of multiplet splitting and line radiation imprisonment during the discharge quenching by intense argon injection in ITER. In this paper, the fine structure of energy levels and the noncoronal collisional-radiative kinetics for the radiating excited state are used. For the radiation of two argon ions, Ar+15 and Ar+3, which have spectral lines of high intensity and could be used for plasma diagnostics, it is shown that the optical thickness for the ionic strongest lines has no significant effect on the total power losses of plasma radiation in the considered quenching scenario (massive argon injection in the 15 MA, Q 10 basic scenario in ITER, carried out at the quasi-stationary stage of the discharge, flat-top of the current). The most significant effect appears to be the multiplet splitting of atomic levels, which provides an increase in the radiative losses, e.g., by a factor of 2 for low-ionized atoms at low temperatures, because the resolution of the fine structure of atomic levels for Δn = 0 transitions leads to a contribution of lower excitation energy than that in the model of multiplet-average radiative transitions.

A simple qualitative model of the influence of grouping of atomic levels on the radiation losses of impurity ions in a near-wall low temperature plasma is proposed using the example of line radiation losses when excited states are populated by impact excitation by plasma electrons. A comparison of the relevant data simulated by the ADAS codes for low-charge ions of argon, neon, and nitrogen ions confirms the predicted effects of possible underestimation or overestimation of radiation losses when the number of atomic levels taken into account in the simulation in the collisional-radiative model decreases.

The characteristics of emission spectra induced by femtosecond laser filaments in air and water aerosol were studied. Spectra were accumulated 100 ns after 0 ns time delay relative to laser pulse. Second positive (2+) N_2( C 1pt^3Π _u^ - B 1pt^3Π _g^) and first negative (1–) N_2^ + ( B 1pt^2Σ _u^ + - X 1pt^2Σ _g^ + ) nitrogen systems were observed. Growth of continuum intensity and noise was observed at transition from filamentation in air to that of in water aerosol. Intensity of 1– system line decreased more strongly in comparison with 2+ system lines for filamentation in water aerosol what explained by quenching collisions of emitters by water molecules. Translational and vibrational temperatures were measured, 329 and 3470 K (filamentation in air), 356 and 3546 K (filamentation in water aerosol).

Integral radiative losses of deuterons, tritons, and alpha particles on impurity tungsten ions have been calculated for the first time within the statistical theory of the atom for the designed operational regimes of the ITER and EU-DEMO tokamak reactors. It was previously shown within the statistical theory of the atom that specific radiative losses of this new ion channel are comparable with specific electron radiative losses, which also include losses due to bremsstrahlung, radiative and dielectron recombination. Integral radiative losses have been calculated within the numerical model of fusion power isolines, which was previously proposed to study the operational space and design regimes of tokamak reactors. Spatial distributions of the tungsten density with various degrees of peaking in the center of a plasma column have been considered to study the influence of the accumulation of the impurity on integral radiative losses. It has been found that the studied new channel adds about 20 and 30% to the total integral radiative losses on tungsten in the ITER and E-U‑DEMO tokamak reactors, respectively. Consequently, this channel of radiative losses should be taken into account to examine in more detail the working scenarios of these devices.

A generalized kinetic model of atomic level populations in an optically dense plasma excited by laser pulses of arbitrary duration is formulated and studied. This model is based on a nonstationary expression for the probability of excitation of an atomic transition and takes into account the effects of laser pulse penetration into an optically dense medium. A universal formula for the excitation probability as a function of time and propagation length is derived and applied to the case of a Lorentzian spectral profile of an atomic transition excited by a laser pulse with a Gaussian envelope. The features of nonstationary excitation probabilities are presented for different optical depths of the plasma, laser pulse durations, and carrier frequencies. The formulas derived here will be useful for the description of atomic populations excited by laser pulses under realistic conditions of dense plasmas.

The statistical method is applied to calculate the new channel of radiative losses of alpha particles, deuterons, and tritons when exciting multielectron impurity ions in thermonuclear plasma. A new statistical model of Coulomb–Born atom excitation is elaborated accounting for the normalization of transition probabilities. The radiative losses of multielectron tungsten ions are calculated within the scope of two statistical plasma models—local plasma frequency (LPF) and Coulomb–Born models. The results of both models are in a good agreement with each other; the sum of the radiative losses of fast heavy ions are of the same order of magnitude as those of electrons, including bremsstrahlung and radiative and dielectronic recombination.

Scattering of ultrashort laser pulses (USP) in optically dense plasma is presented, accounting for the peculiarities of ultrashort electromagnetic interaction and absorption of radiation in plasmas. The results are presented in terms of a universal dimensionless total scattering coefficient (TSC). A universal closed expression for TSC is derived and analyzed. Numerical calculations of TSC are carried out for the special case of USP resonance scattering on H-like ions in hot plasmas. Fine structure splitting of the resonant transition and Doppler broadening are taken into account. The dependences of the TSC on USP parameters and the optical thickness of plasma layers are derived. (c) 2024 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license.

The effect of thermodynamic nonequilibrium of hydrogen isotope recycling, which consists in significant deviation of the velocity distribution function (VDF) of neutral hydrogen isotope atoms from the Maxwellian VDF, on the passive signal of the charge-exchange recombination spectroscopy (CXRS diagnostics) of edge plasma in tokamaks is analyzed using the ITER tokamak reactor as an example. The calculations of the VDF for atomic and molecular deuterium are carried out using the three-dimensional Monte Carlo code EIRENE as a part of the two-dimensional transport code SOLPS and the semi-analytical Ballistic Model BM1D2V, which is one-dimensional in coordinate and two-dimensional in projections of atomic velocity. The source of level population of the Be IV beryllium ion, the line radiation of which is used in the CXRS diagnostics, is calculated for the above two methods of calculating the VDF and the average atomic kinetic energy, as well as in the case of neglecting the thermodynamic nonequilibrium of recycling, when the temperature of atoms is equal to the temperature of the plasma ions. The calculations of the cross section for the charge-exchange reaction of beryllium ions Be V on deuterium atoms using the ARSENY code and other codes and the erosion kinetics of the beryllium first wall using the three-dimensional code ERO2.0 are used. The calculations of the level populations of the Be IV beryllium ion using the nl-KinRyd code, the luminosity of the ions, and the passive charge-exchange radiation intensity on the observation chord are carried out for the three indicated cases of the VDF of deuterium atoms. A significant dependence of the results of the conducted predictive modeling on the thermodynamic nonequilibrium of recycling is shown.

The effect of the duration of laser pulses of 40 and 650 fs with an energy of 1.1 mJ at a wavelength of 800 nm on the spectral-temporal characteristics of plasma during femtosecond laser-induced breakdown spectroscopy of human hair has been studied. The time dependences of the radiation line intensities of Ca I 422.6 nm, C I 193.1 nm, C I 247.8 nm, Ca II 396.8 nm, Mg II 279.5 nm, Zn II 206.2 nm and the continuous plasma spectrum in the range from 0 to 1 microseconds are obtained

Integral radiative losses of deuterons, tritons, and alpha particles on impurity tungsten ions have been calculated for the first time within the statistical theory of the atom for the designed operational regimes of the ITER and EU-DEMO tokamak reactors. It was previously shown within the statistical theory of the atom that specific radiative losses of this new ion channel are comparable with specific electron radiative losses, which also include losses due to bremsstrahlung, radiative and dielectron recombination. Integral radiative losses have been calculated within the numerical model of fusion power isolines, which was previously proposed to study the operational space and design regimes of tokamak reactors. Spatial distributions of the tungsten density with various degrees of peaking in the center of a plasma column have been considered to study the influence of the accumulation of the impurity on integral radiative losses. It has been found that the studied new channel adds about 20 and 30% to the total integral radiative losses on tungsten in the ITER and E-U‑DEMO tokamak reactors, respectively. Consequently, this channel of radiative losses should be taken into account to examine in more detail the working scenarios of these devices.

This article is devoted to the life and work of the outstanding theoretical physicist, creator of world-famous scientific schools in radiophysics, plasma physics, and controlled thermonuclear fusion, Academician Mikhail Aleksandrovich Leontovich (1903–1981). His achievements in basic physics contributed to significant advances in applied research in many fields. The uniqueness of the scientific style and civic appearance of M.A. Leontovich, the lessons of his creative biography remain significant today, especially for young scientists, setting an example of selfless service to science.

The present review is dedicated to the problem of an array of transitions between highly-excited atomic levels. Hydrogen atoms and hydrogen-like ions in plasmas are considered here. The presented methods focus on calculation of spectral line shapes. Fast and simple methods of universal ionic profile calculation for the Hnα (Δn=1) and Hnβ (Δn=2) spectral lines are demonstrated. The universal dipole matrix elements formulas for the Hnα and Hnβ transitions are presented. A fast method for spectral line shape calculations in the presence of an external magnetic field using the formulas for universal dipole matrix elements is proposed. This approach accounts for the Doppler and Stark–Zeeman broadening mechanisms. Ion dynamics effects are treated via the frequency fluctuation model. The accuracy of the presented model is discussed. A comparison of this approach with experimental data and the results of molecular dynamics simulation is demonstrated. The kinetics equation for the populations of highly-excited ionic states is solved in the parabolic representation. The population source associated with dielectronic recombination is considered.

The effect of the thermal motion of ions on the spectra of multicharged ions in dense plasma is investigated. An analytical expression is obtained for the frequency of jumps in the amplitude of the ion micropole. A modification of the frequency-fluctuation model technique is proposed, which allows taking into account the dependence of the frequency of jumps of the ion microfield on the energy shift. A new approach to the diagnosis of plasma density by the area of the dip in the center of the spectral lines is presented. Calculations of the spectra of argon impurity in deuterium plasma are given.

We have obtained limits of detection (LoD) of Al (396.15 nm), Ba (553.35 nm), Ca (422.67 nm), Mg (285.21 nm), Na (588.99 nm) and Mn (403.08 nm) in liquid-droplet aerosol by filament-induced spectroscopy (R-FIBS) using ultrashort laser pulses (60 fs, 800 nm, 4.4 mJ). The limit of detection of the Na by emission line (588.99 nm) in a liquid-droplet aerosol was obtained by laser induced breakdown spectroscopy (LIBS) using short laser pulses (7 ns, 1064 nm, 550 mJ). The obtained results were compared within the framework of the methods used.

The results obtained by experimentally and theoretically studying the yield of the promising nuclear-fusion reaction $${}^{11}$$ B( $$p,3\alpha$$ ) initiated by powerful picosecond laser radiation of intensity $$3\times 10^{18}$$ W/cm $${}^{2}$$ are presented. A new procedure that relies on a simultaneous detection of the yield of alpha particles and the neutron yield in the reference reaction $${}^{11}$$ B $$(p,n)^{11}$$ C and which permits reaching a high precision of measurements is employed. The measured alpha-particle yield per pulse in the reaction $${}^{11}$$ B( $$p,3\alpha$$ ) is 10 $${}^{9}$$ particles in 4 $$\pi$$ sr at the above laser-pulse parameters. The results of a numerical particle-in-cell (PIC) simulation of the nuclear-fusion reaction $${}^{11}$$ B( $$p,3\alpha$$ ) proceeding in a solid-state boron target are presented. These results on the alpha-particle yield per pulse in the reaction $${}^{11}$$ B( $$p,3\alpha$$ ) agree fairly well with experimental results.

The saturation effect during the excitation of a two-level system by laser pulses is investigated in the framework of two approaches: excitation probability based on Karplus–Schwinger spectral profile and exact solution of Bloch equations. Simple analytical expression for the excitation probability by exponential pulse is derived. The excitation spectra obtained using this expression were compared with the result of solving the Bloch equations for various values of the pulse duration and the Rabi frequency, which describes the strength of the electromagnetic interaction. It is shown that in the case of long pulses, there is a satisfactory correspondence between the two approaches, but in short-pulse limit and strong saturation, the probability description based on Karplus–Schwinger spectral profile and perturbation theory does not provide satisfactory results.

Получены значения пределов обнаружения Al (396,15нм), Ba (553,35 нм), Ca (422,67 нм), Mg (285,21 нм), Na (588,99 нм) и Mn (403,08 нм) в жидко-капельном аэрозоле методом филаментно-индуцированной спектроскопии (R-FIBS) с использованием ультракоротких лазерных импульсов (60фс, 800 нм, 4,4 мДж). Получено значение предела обнаружения натрия по линии Na (588,99 нм) в жидко-капельном аэрозоле методом лазерной искровой спектроскопии (LIBS) с использованием лазерных импульсов короткой длительности (7 нс, 1064 нм, 550 мДж). Проведено сравнение полученных результатов в рамках используемых методов.

Data on the cross section and kinetic rate of charge exchange (CX) between the bare beryllium nucleus, the ion Be(+4) and the neutral hydrogen atom are of great interest for visible-range high-resolution spectroscopy in the ITER tokamak because beryllium is intended as the material for the first wall in the main chamber. Here an analysis of available data is presented, and the data needs are formulated. Besides the active probe signal produced by the CX of the diagnostic hydrogen neutral beam with impurity ions in plasma, a passive signal produced by the CX of impurity ions with cold edge plasma is also important, as it shows in observation data from the JET (Joint European Torus) tokamak with an ITER-like beryllium wall. Data in the range of a few eV/amu to ~100 eV/amu (amu stands for the atomic mass unit) needed for simulations of level populations for principal and orbital quantum numbers in the emitting beryllium ions Be(+3) can be obtained with the help of two-dimensional kinetic codes. The lack of literature data, especially for data resolved in orbital quantum numbers, has instigated us to make numerical calculations with the ARSENY code. A comparison of the results obtained for the one-centre Coulomb problem using an analytic approach and for the two-centre problem using numerical simulations is presented.