Table of contents

A.P. Kuznetsov and S.V. Genisaretskaya

III Conference on Plasma and Laser Research and Technologies took place on January 24^th until January 27^th, 2017 at the National Research Nuclear University "MEPhI" (NRNU MEPhI). The Conference was organized by the Institute for Laser and Plasma Technologies and was supported by the Competitiveness Program of NRNU MEPhI.

The conference program consisted of nine sections:

• Laser physics and its application

• Plasma physics and its application

• Laser, plasma and radiation technologies in industry

• Physics of extreme light fields

• Controlled thermonuclear fusion

• Modern problems of theoretical physics

• Challenges in physics of solid state, functional materials and nanosystems

• Particle accelerators and radiation technologies

• Modern trends of quantum metrology.

The conference is based on scientific fields as follows:

• Laser, plasma and radiation technologies in industry, energetic, medicine;

• Photonics, quantum metrology, optical information processing;

• New functional materials, metamaterials, "smart" alloys and quantum systems;

• Ultrahigh optical fields, high-power lasers, Mega Science facilities;

• High-temperature plasma physics, environmentally-friendly energetic based on controlled thermonuclear fusion;

• Spectroscopic synchrotron, neutron, laser research methods, quantum mechanical calculation and computer modelling of condensed media and nanostructures.

More than 250 specialists took part in the Conference. They represented leading Russian scientific research centers and universities (National Research Centre "Kurchatov Institute", A.M. Prokhorov General Physics Institute, P.N. Lebedev Physical Institute, Troitsk Institute for Innovation and Fusion Research, Joint Institute for Nuclear Research, Moscow Institute of Physics and Tecnology and others) and leading scientific centers and universities from Germany, France, USA, Canada, Japan.

We would like to thank heartily all of the speakers, participants, organizing and program committee members for their contribution to the conference.

All papers published in this volume of Journal of Physics: Conference Series have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

Algorithm for the mathematical modelling of a fiber oscillator with a hybrid modulator based on a nonlinear fiber mirror and single-walled carbon nanotubes is suggested. It is based on a numerical solution of the nonlinear Schrödinger equation. Using numerical simulation, optimum NOLM coupler ratio, laser spot diameter on the sample preventing sample degradation and high modulator effect are determined.It is shown that hybrid modulator accelerates the self-starting process and decreases the output pulse duration up to 10%.

We have represented a system description used to study of the kinematic parameters of processes of destruction of chondrites under the action of intense shock waves. Interferometric method of measuring speed PDV was the basis for a compact, easy-to-use device intended for the analysis products of target destruction. Using the Fourier transform method of analysis, the dynamic rates of expansion for chondrite targets in interaction with high-power laser radiation and the dependence of the shock wave velocity on the thickness of the target were obtained.

The basic goal of this work is the development of investigation technique of space-time parameters of broadband oscillator of the powerful Luch Facility of the Russian Federal Nuclear Center designed to smooth radiation profile during passage of fiber optical line. The smoothing is achieved by means of modes mixing because of wave length dispersion in fiber optics, as a result the speckled radiation structure is removed. The optical scheme for recording radiation and the photochronograph with slot scan have been prepared to carry out measurements. The measurements of duration, impulse shape and space-time heterogeneity of laser radiation at output of formation system of reference radiation with fiber optical smoothing were carried out using that developed technique.

In this paper we consider the method of obtaining THz radiation by difference frequency generation (DFG) of multiline CO₂ laser. For this purpose a multiline CO₂ laser with Q-switching was created. The three strongest lines, 9 R(18), 9 P(20) and 9 P(22) with wavelengths ∼9.28, ∼9.55 and ∼9.57 μm respectively, held 85% of CO₂ laser power, and can be used to obtain difference frequency at a wavelength of ∼310 μm. DFG of other spectral lines fall within the range of 263 ÷ 8100 μm. Different nonlinear crystals for DFG and filters to separate THz radiation were considered.

Numerical simulation of sum frequency generation spectrum method was elaborated by considering dynamics of generation of every Q-switched CO laser rotational-vibrational lines. It resulted in decreasing of total power by 25% and disappearing approximately 15% lines in comparison with calculation proceeded without taking dynamics into account.

The spectrum of low-pressure cryogenic CO laser operated in Q-switched mode was measured at frequencies of 70 Hz and 120 Hz. CO laser spectrum consisted of 115 spectral lines in the wavelength range from 4.89 μm to 6.54 μm at 70 Hz, and 102 lines in the wavelength range from 4.90 μm to 6.44 μm at 120 Hz. For the first time the dynamics of generation on each spectral line for full CO laser spectrum were measured. We identified rotational-vibrational transitions and analyzed the processes, which affect the formation of the CO laser spectrum. This data were taken into account to determine the peak powers of all the spectral lines correctly.

For the first time, a quasi-spherical current implosion has been experimentally realized on a multimegaampere facility with the peak current of up to 4 MA and a soft X-ray source has been created with high radiation power density on its surface of up to 3 TW/cm². An increase in the energy density at the centre of the source of soft X-ray radiation (SXR) was experimentally observed upon compression of quasi-spherical arrays with the linear-mass profiling. In this case, the average power density on the surface of the SXR source is three times higher than for implosions of cylindrical arrays of the same mass and close values of the discharge current. Obtained experimental data are compared with the results of modelling the current implosion of multi-wire arrays performed with the help of a three-dimensional radiation-magneto-hydrodynamic code.

A model is elaborated for interpreting the initial stage of the fast nonlocal transport events, which exhibit immediate response, in the diffusion time scale, of the spatial profile of electron temperature to its local perturbation, while the net heat flux is directed opposite to ordinary diffusion (i.e. along the temperature gradient). We solve the inverse problem of recovering the kernel of the integral equation, which describes nonlocal (superdiffusive) transport of energy due to emission and absorption of electromagnetic (EM) waves with long free path and strong reflection from the vacuum vessel's wall. To allow for the errors of experimental data, we use the method based on the regularized (in the framework of an ill-posed problem, using the parametric models) approximation of available experimental data. The model is applied to interpreting the data from stellarator LHD and tokamak TFTR. The EM wave transport is considered here in the single-group approximation, however the limitations of the physics model enable us to identify the spectral range of the EM waves which might be responsible for the observed phenomenon.

The critical density limit in tokamaks is investigated. It is shown that the equality of the input power and power radiated by impurities corresponds to the Greenwald limit. In Ohmic tokamak plasmas the auxiliary heating may increase the density limit, as it has been shown in experiments. The radiated power threshold for plasmas with heavy impurities, observed in experiments, is derived. Radiation produced by heavy impurities is spread practically uniformly along the plasma radius in contrast to the radiation of light impurities. The effective heating power is decreased by radiation losses and, as a consequence, becomes lower than the threshold for the H-L transition. If the input power is close to the radiated one, the disruption occurs.

It is shown that the ignition may be achieved in tokamaks with the modulated power source. The time-averaged source power may be smaller than the steady-state source power, which is sufficient for the ignition. Nevertheless, the maximal power must be large enough, because the ignition must be achieved within a finite time interval.

This paper presents a mathematical model, numerical method and results of the computer analysis of the compression process and the energy transfer in the target plasma, used in magneto-inertial fusion. The computer simulation of the compression process of magnetized cylindrical target by high-power laser pulse is presented.

The paper presents the comparison of the structures and physical properties of films and dust particles. They are prepared on the vacuum chamber walls from the arc-discharge plasma and tokamak plasma. The morphology of the surface, microstructure, color range, grain-size distribution, and elemental and phase composition of films and micro particles have been compared. It was found that the films and powders have properties of nanocrystal materials. The structure, surface morphology and some properties of the arc-discharge plasma particles are similar to the structures and properties of the particles deposited on the TOKAMAK walls.

Paper presents theoretical investigations of spatial particle separation in modified linear Paul trap. In the simulations two upper electrodes of four of the trap were angled upwards to study particle separation at different geometries (interelectrode distances) at the same time. To simulate particle motion the Brownian dynamics has been used. Simulations were carried out in the assumption of spherical particles and that particles chargesare proportional to particle surface area. In the simulations particles occupied specific lengths according their charge-to-mass ratio.

Human activity is associated with the permanent emergence of a very wide range of waste streams. The most widely used treatment of waste is thermal processing such as incineration. An alternative environmentally friendly process is based on thermal plasma technology which is a very flexible tool because it allows to operate in a wide temperature range with almost any chemical composition of waste and chemicals needed for processing this waste. It allows the conversion of organic waste into energy or chemical substances as well as the destruction of toxic organic compounds in a scenario that for each specific type of waste can be considered optimal, both in terms of energy efficiency and environmental safety.

Current-plasma sheath dynamics in coaxial pulsed plasma system was simulated in this work by means of one-fluid MHD code and two-dimensional "snow plough" model.

This paper presents the new experimental results concerning acceleration of deuterium ions extracted from laser plasma in the rapid-growing nonuniform magnetic field in order to initiate the nuclear reactions D(d, n)³He and T(d, n)⁴He. For obtaining of laser plasma a Nd: YAG laser (λ = 1,06 μm) that generates in Q-switched mode the radiation pulses with the energy W ≤ 0,85 J and duration of τ ≈ 10 ns was used. Rapid-growing magnetic field was created with the discharge of Arkadyev-Marx pulsed-voltage generator to conical coil with the inductance of 0,65 μΗ. At characteristic discharge time of 30 ns, the rate of magnetic field growth achieved 2·10⁷ T/s. Ion velocity was determined with the time-of-flight technique. During the experiment on deuterium plasma an ion flux velocity of ∼3 · 10⁸ cm/s was obtained, which corresponds to the deuteron energy of ∼100 keV. Herewith, for target power density of ∼5·10¹¹ W/cm² obtaining of up to 10¹⁵ of accelerated deuterons and up to 10⁸ of neutrons per a pulse is expected.

A consideration is given to the effect of capillary discharge torch on metal foils. The spectral characteristics of plasma have been measured in visible and ultraviolet ranges and plasma temperature has been determined in the area of interaction. The properties of autonomous plasma areas appearing in case of this interaction are being investigated. A study of plasma areas collision with the surface of liquid nitrogen has been presented. The motion of plasma areas in permanent electric field has been studied. A possible structure of plasma areas is being discussed.

The parameters of discharge close to electrolyte surface have been investigated in the work. The current-voltage discharge characteristics have been measured for the main discharge modes. The electric discharge oscillations have been studied and spectra determined in the range of 10 kHz–300 MHz for two electrolyte compositions. The study of discharge radiation in the visible and ultraviolet ranges of electromagnetic range has been carried out and plasma temperature determined. The influence of discharge on microstructure of electrodes surface has been investigated.

Precise knowledge of the differential inverse inelastic mean free path (DIIMFP) and differential surface excitation probability (DSEP) of Tungsten is essential for many fields of material science. In this paper, a fitting algorithm is applied for extracting DIIMFP and DSEP from X-ray photoelectron spectra and electron energy loss spectra. The algorithm uses the partial intensity approach as a forward model, in which a spectrum is given as a weighted sum of cross-convolved DIIMFPs and DSEPs. The weights are obtained as solutions of the Riccati and Lyapunov equations derived from the invariant imbedding principle. The inversion algorithm utilizes the parametrization of DIIMFPs and DSEPs on the base of a classical Lorentz oscillator. Unknown parameters of the model are found by using the fitting procedure, which minimizes the residual between measured spectra and forward simulations. It is found that the surface layer of Tungsten contains several sublayers with corresponding Langmuir resonances. The thicknesses of these sublayers are proportional to the periods of corresponding Langmuir oscillations, as predicted by the theory of R.H. Ritchie.

The results of the comparative analysis of low-temperature desorption of deuterium from tungsten coated with aluminum and yttrium films under the irradiation by hydrogen plasma with oxygen impurity are presented. The irradiation of aluminum or yttrium coating by H₂+1%O₂ plasma leads to the desorption of implanted deuterium from the samples. It was shown that the number of atoms desorbed depends on the sign of enthalpy of hydrogen solution in the metal film.

The results of a study of a surface formed by high-temperature plasma loads on refractory metals such as tungsten and stainless steel are presented. There is an inhomogeneous stochastic clustering of the surface with self-similarity properties of the granularity structure from nanoscale to macro scale, similar to the previously described fractal structure of carbon materials from fusion device. The statistical characteristics of hierarchical granularity and scale invariance are estimated that qualitatively differ from the properties of the roughness of the Brownian surface, which is possibly due to the universal mechanisms of stochastic clustering of materials under the influence of high-temperature plasma.

The analysis of erosion and redeposition processes plays an important role in the physics of fusion devices. In this work we present the results of computer simulation of plasma-facing materials surface analysis by use of the keV-energy proton scattering spectroscopy. It is shown that this technique can be used for the non-destructive analysis of thin surface layers. Energy spectra that correspond to different scattering and target parameters are presented.

Calculations of the energy of the H-W system were performed using DFT method based on plane waves. Adsorption energies, equilibrium states, vibration spectra, saddle points, activation energies of jumps, and diffusion paths have been analyzed for H atom on W(100) and W(110). Diffusion coefficient for H on W(110) agrees very well with experimental data.

Tungsten fuzz is a material formatted due to interaction of helium plasma with tungsten surface. This material consists of large number of thin nanostructures "growing" on the tungsten surface and having enhanced field emission properties. However, the calculation of field amplification factor from emission current-voltage characteristic gives large value which is not correlated with geometrical parameters of the nanostructures. Thermal field electron emission model that takes into account the Joule heating by emission current is presented in this work. This model predicts qualitatively similar current values corresponding to experiment and explains enhanced field amplification factor from the current-voltage characteristic.

A possible application of a lithium emitter-collector scheme to the T-15MD tokamak is considered. 2D simulations with the SOLPS4.3 code package indicate that the outer midplane is the optimal position for the lithium emitter. In the magnetic configuration analysed, lithium deposition is primarily localized in the upper outer divertor. Lithium radiation enhancement due to non-coronal effects for the case studied is about a factor of 6. However, although much higher than normally observed for higher Z impurities (such as neon), this enhancement is clearly insufficient to provide significant energy dissipation, unless the lithium inventory in the edge becomes close to the deuterium one.

The results of experiments on the interaction of nanosecond laser radiation (wavelength of 1.06 μm and a radiation power density of 10¹²–10¹³ W/cm²) with targets from various materials (Cu, (C₂H₄)_n, TAC) are presented in the paper. In the experiments images of the plasma in own optical radiation in the wavelength range 0.4–1.1 μm were obtained. In one shot of laser images at wavelengths corresponding to the radiation of the harmonics 2ω₀, 3/2ω₀, 5/2ω₀, and at the frequency of laser radiation ω₀ were recorded. Using the obtained images the spatial characteristics of the radiating regions of the plasma, as well as the radiated energy for each of the harmonics, were estimated.

The possibility of producing gradient materials, i.e. materials with pre-set distribution of areas having fundamentally different physical and mechanical characteristics, with the help of laser heat treatment was investigated. Using as an example austenitic-martensitic alloys of iron-chromium-nickel, subjected to cold plastic deformation led to formation of martensite, we show that using laser at the temperature higher than the temperature of reverse martensite transformation leads to the formation of areas of high-strength austenite having predetermined form inside the martensite matrix. Influence of austenite areas geometry on mechanical properties of gradient material was studied.

The Raman spectroscopy has been used to analyse ion-induced modifications of carbon PAN-fiber shell due to 10-30 keV Ar⁺ high fluence ion irradiation at normal and oblique incidence in the temperature range from RT to 400 °C. It has shown that formed in ion-induced processes of amorphization, recrystallization and crimping the modifications of PAN-fiber shell are characterized by the presence of the amorphous phase with the A peak in the Raman spectra and the increased intensity of the D peak relative to the G peak in comparison with non-irradiated fiber. Amorphous phase in the PAN-fiber shell is the highest in case of amorphization and the least at the crimping. The increased intensity of the D peak in the Raman spectra and the G peak shift towards higher frequencies during recrystallization and crimping indicates ion-induced nanostructuring of the PAN- fiber shell.

The experimental results of ion-induced crimping of the high-modulus carbon PAN-fibers using nitrogen, neon and argon ions with energies of tens keV are presented. Ion-induced surface nanostructuring of the formed crimps provides more than a hundredfold increase in the specific surface area of the fiber and its shrinkage that retains in thermal processes in the production of composites.

In the present work the experiments on laser cladding of powder Fe-B-Cr-6-2 on samples of steel 20. Metallographic studies of geometric parameters of deposited layers and the depth of the heat affected zone (HAZ). Using is the method of full factorial experiment (FFE) mathematical dependences of the geometrical sizes of the deposited layers of processing modes. Deviation of calculated values from experimental data is not more than 3%.

The paper presents the results of mechanical properties study of the material produced by direct metal laser deposition of VT6 titanium powder. The properties were determined by the results of stretching at tensile testing machine, as well as compared with the properties of the same rolled material. These results show that obtained samples have properties on the level or even higher than that ones of the samples obtained from the rolled material in a certain range of technological regimes.

In present paper a self-consistent model of laser annealing of porous defects in metals is presented. In the proposed model, the defects represent empty isolated pores whose dimensions are much less than thickness of the metal coating. Reduction of porosity occurs due to pore collapse in the molten pool under surface tension forces. In this case the research showed that pore collapse dynamics depends considerably on the pressure in the molten material. From the equality of the negative pressure in the melt and the capillary pressure the applicability bound of the model is determined. It is the critical melting rate of porous material at which pore collapse is still possible.

Mobile laser technological complex MLTC-20 with radiation power 20 kW and radiation wavelength 1.07 μm created in SRC RF TRINITI on the base of a three cw fiber Yb lasers is used successfully at remote cutting of the metalworks at carrying out of the emergency-reduction works on the out of control gas wells. In this work the results of the investigation of the possibility and the efficiency of laser radiation application for remote cutting of metals on the emergency oil wells have been presented. Measurements of the mean absorption coefficient of the radiation of a cw fiber Yb laser under its propagation in a flame of burning oil in dependence on radiation intensity have been carried out. It was shown that at the intensity ~10⁴ W/cm² the absorption coefficient traverses the maximum where its value is equal to ~0.1 cm⁻¹, and at the intensity increasing to the values 10⁵ − 10⁶ W/cm² it stabilizes on a small level ~5·10⁻³ − 10⁻² cm⁻¹. It is established that the maximal velocity and the efficiency of remote cutting of the steel plates with a thickness up to 10 mm by the radiation with the intensity 10⁶ W/cm² exceed these factors at the intensity 10⁴ W/cm². The possibility of the efficient remote cutting of steel plate with a thickness of 60 mm by laser radiation having the power 7.5 kW and the intensity 10⁵ W/cm² has been demonstrated.

Synthesis of oxides, nitrides, and oxynitrides of silicon and aluminium by a pulsed microwave discharge in the mixtures of metal and dielectric powders is described. The microwave pulses were generated by high-power gyrotron (frequency 75 GHz, power up to 550 kW, pulse duration from 0.1 to 15ms). SiO₂ + β-Si₃N₄ (1:1 by molar) and α-Al₂O₃ + AlN (2:1 by molar) mixtures with Mg (1 and 5wt%) were treated in air with microwave pulses with power of 250÷400 kW and duration of 2÷8 ms. It was found that the discharge cannot be initiated for both mixtures in absence of Mg at any pulse power and duration. When 1% of Mg was added, the discharge was observed for both mixtures under 8 ms pulses of 400 kW; however, the amounts of materials produced were not enough for analysis. With 5% of Mg the discharge was observed for both mixtures under 8 ms pulses of 350 kW, and products of the plasma-chemical processes in the Al₂O₃ + AlN mixture were analyzed.

The paper presents the results of metallographic studies and laboratory comparative tests on the adhesion strength of the coating to the substrate and abrasion on the scheme Brinell-Haworth cladding powder coatings on Nickel-based and samples of steel 40X. Strength of adhesion of the first coating layer with a hardness of HRC 38–42 was 400–480 MPa. It is shown that when the hardness of the deposited layer HRC 58–61 wear resistance of the coatings is higher than 40X steel in the normalized and improved in 10 and 4.6 times, respectively.

Possibility of nitriding of internal cylindrical surfaces in plasma of abnormal glow discharge with hollow cathode in the pulse-periodic mode in N₂+H₂ was investigated. Tubes with internal diameters of 6, 8, and 9 mm and with the aspect ratio from 12 to 50 were made a low carbon steel were used. Regimes of the discharge were investigated. Nitrided layers in different parts of the tubes were analyzed.

On the example of glass forming equipment, the surfaces of which must have high wear resistance during repeated contacts with molten glass, a study was made of laser cladding of nickel based alloys on a substrate of gray cast iron. In study the shapes of individual tracks are investigated with varying laser radiation power, processing speed and powder feed rate. The influence of technological parameters on the width and height of the clad is shown. A similarity is found between the two principles of measuring the dilution through linear dimensions and the areas of track in cross section. A high correlation between dilution and laser radiation power over a wide range of speeds has been established, which has made it possible to develop a scheme of control laser cladding process with achieving a low level of dilution in order to minimize the heat effect zone (HAZ).

We report the fabrication of multifunctional coatings via inkjet printing using water-based nanoinks in the form of selenium (Se) and gold (Au) nanoparticle (NP) colloids, prepared by laser ablation of solid targets in deionized water or 50%-isopropyl alcohol solution. Nanoparticles and NP-based coatings were deposited onto silver films, magnetronsputtered to silica-glass substrates, and characterized by means of scanning and transmission electron microscopy (SEM, TEM), UV-vis-IR, Raman and energy-dispersive X-ray spectroscopies.

In this paper, an experimental study of laser dimensional processing of thermoset carbon fiber reinforced plastics with a thickness of 2 and 3 mm was performed. In the process of work test rig setup based on picosecond pulsed fiber laser with 1.06 microns wavelength and 30 W average power was developed. Experimental tests were carried out at the maximum average power, with laser beam moved by a galvanometric mirrors system. Cutting tests were executed with different scanning velocity, using different laser modes, number of repetitions, hatching distance and focal plane position without process gas. As a result of the research recommendations for the selection processing mode parameters, providing minimal heat affected zone, good kerf geometry and high cutting speed were produced.

In this work the morphology, the size and the chemical composition of the powders of steel 316L received by the two methods was studied: fusion dispersion by a gas stream and reduction of metal chlorides with the subsequent plasma atomization of the received powder particles. The powder particles received by the first method have a spherical shape (aspect ratio 1,0–1,2) with an average size of 77 μm and are characterized by the absence of internal porosity. Particles of the powder received by the second method also have a spherical shape and faultless structure, however, their chemical composition may vary in different particles. The average size of particles is 32 μm. Though the obtained powders had different properties, the experimental samples received by DLD technology demonstrated by equally high durability (Ultimate strength is 623±5 and of 623±18 MPa respectively) and plasticity (38 and 41% respectively). It is established that mechanical properties of DLD samples increase for 7-10% after treatment of the surface.

The article presents the results of the computer simulation in the Solid Works using the method of finite elements. In the research described a computer model that was tested on experimental sample that was made of steel 30KHGSA. Data of thermal processes and residual stresses in a sample after laser processing were received during the research. Calculations of the depth of the hardened zones and the strength of the prototype were obtained during the simulation. The process of laser hardening a "Water jet engine sleeve" was simulated in the research. The results and conclusions obtained during this work are given in the conclusion.

The possibility of a direct synthesis of hydrogenated graphene in decomposition of methane by means of low-temperature plasma was investigated. A DC plasma torch with an expanding channel-anode, a vortex gas supply and a self-setting arc length was used as a generator of low-temperature plasma. Argon was used as the plasma-forming gas. The temperatures of argon plasma and with methane addition to it were determined on the basis of spectral measurements. The synthesis products were characterized by electron microscopy and thermogravimetry. The effect of hydrogenated graphene as a nanomodifier on the properties of the cubic boron nitride based functional ceramics was investigated.

The problem of small-angle multiple-scattering of circularly polarized light in a two-dimensional medium with large fiberlike inhomogeneities is studied. The attenuation lengths for elements the density matrix are calculated. It is found that with increasing the sample thickness the intensity of waves polarized along the fibers decays faster than the other density matrix elements. With further increase in the thickness, the off-diagonal element which is responsible for correlation between the cross-polarized waves dissapears. In the case of very thick samples the scattered field proves to be polarized perpendicular to the fibers. It is shown that the difference in the attenuation lengths of the density matrix elements results in a non-monotonic depth dependence of the degree of polarization.

We study propagation of an ultrashort pulse of polarized light through a turbid medium with the Reynolds-McCormick phase function. Within the basic mode approach to the vector radiative transfer equation, the temporal profile of the degree of polarization is calculated analytically with the use of the small-angle approximation. The degree of polarization is shown to be described by the self-similar dependence on some combination of the transport scattering coefficient, the temporal delay and the sample thickness. Our results are in excellent agreement with the data of numerical simulations carried out previously for aqueous suspension of polystyrene microspheres.

We study the long-range spatial correlations between intensity fluctuations in speckles formed by multiply scattered light. The correlation function between intensity fluctuations at the opposite boundaries of the slab are analyzed under the conditions of circular polarization memory. It shown that, until the scattered light is depolarized completely, the polarization and scalar contributions to the correlation function are of the same order of magnitude. As the slab thickness increases, their ratio falls off in inverse proportion to the thickness.

The action of relativistic femtosecond laser pulse with peak intensity over 10¹⁹ W/cm² onto low density plasma is studied experimentally and numerically. It is demonstrated that electrons may be accelerated up to the relativistic energy (>500 keV) directly by the strong field of tightly focused laser radiation. In dependence on the peak laser intensity a dominant angle of high energy electrons is observed, which is around 45 degree for experimental intensity. On the basis of particles energy and angular distribution the laser pulse peak intensity may be evaluated.

For calculation of short laser pulse absorption in metal the imaginary part of permittivity, which is simply related to the conductivity, is required. Currently to find the static and dynamic conductivity the Kubo-Greenwood formula is most commonly used. It describes the electromagnetic energy absorption in the one-electron approach. In the present study, this formula is derived directly from the expression for the permittivity expression in the random phase approximation, which in fact is equivalent to the method of the mean field. The detailed analysis of the role of electron-electron interaction in the calculation of the matrix elements of the velocity operator is given. It is shown that in the one-electron random phase approximation the single-particle conductive electron wave functions in the field of fixed ions should be used. The possibility of considering the exchange and correlation effects by means of an amendment to a local function field is discussed.

The properties of charge carriers in doped graphene are considered. The closed set of explicit equations determining the spectrum and wavefunctions of charge carriers for total angular momentum J = M + 1/2 = 0, ±1/2, ±1... is obtained for the case of the Coulomb potential modified at small distances. The critical values Z_cr of the dopant charge at which the energy level with the given quantum numbers crosses the lower continuum boundary are determined. For Z < Z_cr for several values of the orbital angular momentum dependence of the position of the energy level as a function of charge Z is obtained. For Z > Z_cr, the position ε₀ and width γ of the lowest quasidiscrete state, which may manifest itself as a resonance in hole-dopant scattering, are calculated. It's shown that there is no electron-hole pairs creation because of unitarity of the partial scattering matrix.

We study the conductance fluctuations in the crossover between the ballistic and diffusive regimes of phase coherent transport. For a quasi-1D disordered system, the correlation function of the conductance at different frequencies is calculated beyond the diffusion approximation. The result obtained establishes the interrelation between conductance fluctuations in the crossover regime and the characteristics of the disordered system. The frequency dependence of different contributions to the correlation function is analyzed at subdiffusion length scales.

The results of accuracy analysis of automodel solutions for Lévy flight-based transport on a uniform background are presented. These approximate solutions have been obtained for Green's function of the following equations: the non-stationary Biberman-Holstein equation for three-dimensional (3D) radiative transfer in plasma and gases, for various (Doppler, Lorentz, Voigt and Holtsmark) spectral line shapes, and the 1D transport equation with a simple longtailed step-length probability distribution function with various power-law exponents. The results suggest the possibility of substantial extension of the developed method of automodel solution to other fields far beyond physics.

This paper deals with the analysis of the perturbation growth at the interface between the colliding mediums, one of them has an initial perturbation field of density. The main difference of this hydrodynamic instability from the classical Richtmyer–Meshkov instability is the nature of the initial disturbance. The analyzed hydrodynamic instability is caused by the initial perturbation of the medium density.

The time evolution of interface between two mediums has been studied analytically in nonlinear approximation. The problem has been solved for the third-order corrections to hydrodynamic quantities. Nonlinear interactions cause the appearance of surface sound wave near the contact discontinuity. This wave decreases the growth of the spike velocity. Spike and bubble evolutions have a saturation stage.

The numerical calculations confirm the results of the theoretical analysis.

Crystal plasticity finite element method (CPFEM) is a powerful tool for modeling the various deformation problems, which takes into account the different plasticity mechanisms at microscale of grain sizes and contribution of anisotropic behavior of each grain to macroscopic deformation pattern. Using this method we simulated deformation and plasticity of high explosive HMX produced by relatively low velocity impact. It was found that such plastic deformations of grains cause local heating which is sufficient to induce chemical reactions.

We study equation of state of cold and dense baryon matter within the relativistic mean-field framework with hadron masses and coupling constants dependent on the mean scalar field. Previously constructed models with included hyperons and Δ isobars are extended taking into account possibility of the condensation of charged ρ mesons. We demonstrate that the results obtained in the models with the charged ρ-meson condensation taken into account exhibit a strong model dependence. In some of our (so-called KVORcut-based) models the charged ρ condensation does not significantly affect the value of the neutron star maximum mass. In other (so called MKVOR-based) models the neutron star maximum mass decreases substantially. All thus constructed models pass the observational constraint on the minimal value of the maximum neutron star mass.

We consider a hot isospin-symmetric pion gas with the dynamically fixed number of particles in the model with a λφ⁴ interaction. In the thermodynamic limit, for temperature above the critical value for the Bose-Einstein condensation we calculate the effective pion mass, the chemical potential and the normalized variance. In contrast to the ideal gas, the normalized variance remains finite in the critical point of the Bose-Einstein condensation.

Motivated by recent developments in atomic frequency standards employing the effect of coherent population trapping (CPT), we propose a theoretical framework for the frequency modulation spectroscopy of the CPT resonances. Under realistic assumptions we provide simple yet non-trivial analytical formulae for the major spectroscopic signals such as the CPT resonance line and the in-phase/quadrature responses. We discuss the influence of the light shift and, in particular, derive a simple expression for the displacement of the resonance as a function of modulation index. The performance of the model is checked against numerical simulations, the agreement is good to perfect. The obtained results can be used in more general models accounting for light absorption in the thick optical medium.

MgB₂ may be the future superconducting wire material for industrial magnets due to it's higher operation temperature and potentially lower cost than low temperature superconductors (LTS) have. We designed a compact cryomagnetic system with the use of MgB₂. The possibility of creating a magnet with a central field of 5 T from a commercial MgB₂ wire by the "react and wound" method was investigated. The magnetic system is cooled by a cryocooler through a copper bus. The magnet has a warm bore diameter of 4 cm. The design of a magnet consisting of three concentric solenoids is proposed: an internal one of high-temperature superconductor (HTS), an average of MgB₂, and an external of NbTi. The operating current of the system is 100 A. Two pairs of current leads are used. A separate pair of current leads for power supplying NbTi coil allows testing of MgB₂ and HTS coils in an external field. The load curves for each of the magnets are calculated.

In this work it is presented a computational model of a magnetic levitation system based on stacks of high-temperature second generation superconducting tapes (HTS) GdBa2Cu3O7-x. Calculated magnetic field and the current distributions in the system for different stacks geometries in the zero-field cooling mode are also presented. The magnetization curves of the stacks in the external field of a permanent NdFeB magnet and the levitation force dependence on the gap between the magnet and the HTS tapes stack were obtained. A model of the magnetic system, oriented to levitation application, is given. Results of modeling were compared with the experimental data.

The temperature dependence of the EXAFS-spectra measured above the K absorption edge of As in superconducting (T_c = 13.5 K) single crystals of LaFe_0.89Co_0.11AsO were investigated. Analysis of the spectra in the harmonic approximation revealed anomalies in the temperature dependence of the Debye-Waller factor for As-Fe interatomic bond which correlated with the temperature dependence of electrical resistivity, the coefficient of thermal expansion and magnetic susceptibility given in literature. Taking into account that similar anomalies were earlier observed in superconducting oxides based on BaBiO₃ and in cuprates we conducted the EXAFS spectra analysis in the anharmonic approximation using the potential of arbitrary shape for As-Fe bond vibrations. It was shown that the double-well approximation describes the temperature dependence of the EXAFS spectra better than the harmonic one. The temperature dependence of tunneling frequency and a distance between the wells for double-well potential were obtained. The results indicate that local structural dynamic heterogeneities have a strong impact on macroscopic properties of iron-based superconductors.

The article discusses the joint solution of the Schrödinger and Poisson equations for two-dimensional semiconductor heterojunction. The application of a triangular potential of well approximation for the calculation of the electron-electron interaction is offered in the paper. The influence of the parameters of the selected approximation was analyzed.

Atomic metallic hydrogen with a symmetry FDDD of a lattice cell is shown to have a stable crystalline structure under hydrostatic compression in the pressure range of 350-500 GPa. The resulting phase is shown to have a stable structure regarding the collapse of the phonon spectrum. Ab-initio simulation method has been used to calculate the structural, electronic, phonon and other characteristics of the normal FDDD metallic phase of hydrogen at a pressure of 350-500 GPA.

Sensitivity of the MIS-sensor to products of thermal decomposition of insulation and jacket of the most common types of cables is investigated. It is shown that hydrogen is evolved under heating the insulation to temperatures not exceeding 250 °C. Registration of the evolved hydrogen by the MIS-sensor can be used for detection of fires at an early stage.

Nanostructured WO_x<3 films were prepared by pulsed laser deposition in air from W target. The pressure of air was varied in a range of 10 – 100 Pa and the temperature of a glassy carbon substrate during the film deposition was 22 or 500°C. For the films deposited at 22°C, thermal post-treatment in air of laboratory humidity at 500°C was applied. The increase of air pressure during PLD at 22°C caused both a decrease in packing density of ball-like amorphous nanoclusters of WO_x and decline of their size. Post-treatment in air at 500 °C has initiated crystallization of the nanoclusters but characteristic morphology of the films was preserved in a whole. The PLD of WO_x on a heated substrate resulted in the formation of nanoneedles and nanosheets. Fairly good catalytic properties in hydrogen evolution reaction (HER) and in electrolytic Pt deposition were revealed for the WO_x films that consisted of loosely packed ball-like nanocrystals possessing a size of ∼20 nm. The catalytic activity of the films consisted of nanoneedles and nanosheets was not good enough. Adjustable electrolytic deposition of Pt on the nanostructured WO_x support film allowed to prepare effective hybrid HER catalyst containing only ∼7 μg/cm² of Pt.

We report preparation of nanoribbons (crossection ∼ 250*25 nm²) by focused ion beam etching of single-crystalline Bi₂Se₃ and detailed measurements of their magnetoresistance at temperatures down to 4.2 K, magnetic field up to 9 T. In a magnetic field parallel to the axis of nanowire the magnetoresistance shows up oscillations. Surprisingly, the Fourier analysis shows the presence not only of oscillations with a period corresponding to the flux quantum (Φ₀ = hc/e), but also oscillations with a period of 2Φ₀ and 4Φ₀. Possible mechanisms of the observed effect are discussed.

The films of tungsten oxides were prepared by pulsed laser ablation of W target in a reactive gas atmosphere (air of laboratory humidity). Optical analysis and ion signal measurements for the laser plume allowed to recognise a threshold gas pressure that suppresses the deposition of non-scattered atomic flux from the plume. When the pressure exceeds about 40 Pa, the films grow due to the deposition of species that could be formed in collisions of W atoms with reactive molecules (e.g., O₂). Kinetic Monte Carlo method was used for modelling film growth. Comparison of the model structures with the experimentally prepared films has shown that the growth mechanism of ballistic deposition at a pressure of 40 Pa could be changed on the diffusion limited aggregation at a pressure of ~100 Pa. Thus, a cauliflower structure of the film transformed to a web-like structure. For good correlation of experimental and model structures of WO_x, a dimension of structural elements in the model should coincide with W-O cluster size.

Nanocomposite a-C(Mo/MoSe_x) thin films containing amorphous carbon matrix a-C, nano-Mo and MoSe_{x ≥2} clusters were obtained by pulsed laser co-deposition of carbon and MoSe₂. The deposition was carried out at room temperature onto a graphite substrate. Atomic content of the MoSe_x≥2 phase did not exceed 25%. The use of a buffer gas at a pressure of 10 Pa allowed to obtain the maximum Se/Mo ratio in the films and to increase the concentration of sp²-hybridized C atoms for high conductivity realization. The formation of MoSe_x≥2 cluster inclusions was the essential factor for activation of hydrogen evolution reaction (HER) in 0.5 M H₂SO₄ aqueous solution. These clusters also promoted cathodic deposition of Pt nanoparticles on the surface of a-C(Mo/MoSe_x) in a H₂SO₄/KCl solution when a Pt anode was used as a source of Pt. Hybrid Pt/a-C(Mo/MoSe_x) thin-film coatings with a low Pt loading (~6 μg/cm²) exhibit excellent HER property, which noticeably exceeds that of relatively thick Pt coating prepared on a graphite substrate by pulsed laser deposition.

The two-dimensional two-orbital Hubbard model is studied with the use of worldline quantum Monte Carlo algorithm. Spectral functions and the density of states for various parameters of the model are obtained in both the undoped and low-doped regimes. The invariance of the Fermi surface with respect to the strength of the interaction is testified. Fermi-liquid parameters of the model are derived.

The simulation of vortex lattice in layered high-temperature superconductor (HTSC) has been done using Monte Carlo method. The case of highly anisotropic superconductor with crossing lattices of Abrikosov and Josephson vortices under applying of tilted magnetic field has been examined. The critical current as a function of absolute value of dc magnetic field, parallel and perpendicular to the anisotropy axis c, has been calculated. The simulations have been done for different anisotropy parameter of HTSC and different concentrations of defects. Configurations of the Josephson vortices in presence of the Abrikosov vortices have been obtained.

In this work, we present the numerical approach to determine the quantum state of a superconductor using the Ginzburg-Landau equations by means of a pseudospectral method. Its convergence is demonstrated by simulation of a test problem. All the analytics is given with details.

The article is devoted to the modelling of small-angle scattering data using the program MIXTURE designed for the study of polydisperse multicomponent mixtures. In this work we present the results of solution stability studies for theoretical small-angle scattering data sets from two-component models. It was demonstrated that the addition of the noise to the data influences the stability range of the restored structural parameters. The recommendations for the optimal minimization schemes that permit to restore the volume size distributions for polydisperse systems are suggested.

We present a numerical approach to study the system of exciton polaritons in an optical resonator under pumping. First task in this problem, is to determine the stationary particle distribution. In the case of low enough temperature, to describe the system correctly one cannot neglect the correlations between particles (including the Bose-Einstein condensate) and should take into account all interaction types present in the model. One of the most promising approaches to describe many-particle interacting systems, is the Quantum Monte Carlo (QMC) method. In this article, we describe a modification of the trajectory algorithm based on the Continuous Time World-Line (CTWL) QMC method to simulate the polaritonic system for various parameters of the problem. The modification is described in details.

Analysis of temperature behavior of the critical current in YBa₂Cu₃O_7−δ films is presented. We demonstrate that the overall current can be separated into two components caused by weak pinning on oxygen vacancies in CuO₂ planes and strong pinning on defects in volume of the superconductor. Temperature dependences of the components are obtained and discussed.

We present the XMCD analysis of as-cast and melt spun Fe₅₀Nd₅₀ samples performed at L_2,3-Nd and K-Fe absorption edges at 5 and 50 K in comparison with macroscopic data of XRD, TEM and magnetic properties measurements. In addition, we have measured the magnetic field dependence of XMCD signal for both types of the samples in magnetic fields up/down to 17 T. The obtained results pointed to the strong difference between structure and magnetic properties of the as-cast and melt spun Fe₅₀Nd₅₀ alloys for both macroscopic and local measurements. The element selective XMCD loops for melt spun alloy show almost identical value of the coercive force H_ci for L₂-Nd and K-Fe edges and practically do not depend on temperature. XMCD loop at K-Fe edge is a sum of contributions of the Fe-based phases. The main Fe-rich phase has high H_ci ≈ 2,4 T as a highly anisotropic phase. The absence of the K-Fe XMCD loop saturation in the field up to 17 T points to presence of the second Nd-rich Nd-Fe phase which is ferromagnetic at temperature lower than 50 K. In accordance to the TEM results these both phases may coexist as the mixture of nanocrystals which was formed as a result of decomposition of the amorphous-like matrix phase. The XMCD loop at L₂-Nd edge with H_ci ≈ 1,9 T is the sum of contributions from two Nd-based phases: hard Fe-rich phase (H_ci ≈ 2,4 T) and Nd-Fe matrix phase of medium hardness with H_ci ≈ 1,3 T. The macroscopic loop showed the higher H_ci compared to XMCD loops. Such discrepancy may be caused by the fact that XMCD signal is collected from a 5-10 mcm thick surface layer, which contains many defects that reduce anisotropy and coercivity.

The influence of shocks of different intensity on the structure and properties of multifilamentary superconducting tapes of Bi₂Sr₂Ca₂Cu₃O_10+x (Bi-2223) and MgB₂ compounds was studied. The Plasma Focus setup was used to produce the plasma shock waves, and a specially designed setup was utilized for the mechanical shock treatment. The experiments have shown a possibility to increase the critical current of MgB₂ tapes by more than 60% in magnetic fields of 1.5-2.0 T due to the treatment. The critical current increase is caused by homogeneity improvement, densification of superconducting filaments and the pinning enhancement.

By using the Monte-Carlo method, the dependencies of transport characteristics of a type-II superconductor on the degree of bending strain applied to the sample have been numerically studied. Multiple series of voltage-current characteristics have been acquired for a sample of a high-temperature superconductor for different numbers of strain-induced cracks, as well as various point defects concentrations and different values of external magnetic field. Some peculiarities of the voltage-current characteristics have been detected. Average vortex configurations have been acquired showing that in the points of peculiarities the vortex lattice "freezes" in spaces between cracks. The results for the increasing number of cracks have shown a significant degradation of critical current density.

We present results of study of structure and electrical conductivity of the nanostructured ceramics BiFeO₃ measured for direct and alternating currents (from 1 kHz to 10 MHz) in the temperature range 25-500 °C. The power-law nature of the frequency dependence of the conductivity is discussed in the framework of the model of the correlated barrier jumps of charge carriers, presumably between two- and trivalent iron ions Fe²⁺ → Fe^{3 +}.

Superconducting nanostructured ceramics based on YBa₂Cu₃O_7-δ were made of nanopowder obtained by burning nitrate-organic precursors. The structure, morphology, electrical resistivity, and density of ceramics were studied. Various porosity values of the ceramics were achieved by preliminary heat treatment of the nanopowder. The features of conductivity and the reason for increase of the of the superconducting transition temperature in these materials are discussed.

Our paper is devoted to a compact economic magnetic facility, which is equipped by a 300 kJ capacitor bank. The facility is designed for the exploration of magnetic and optical substance properties under magnetic fields up to 50 T and under cryogenic temperatures. The cyclotron resonance and quantum Hall effect measurement results are presented for semiconductor heterostructures HgTe/HgCdTe with quantum wells.

The main purpose of the work is to improve the magnetic and transport characteristics of 2G HTS tapes by creating an ordered array of artificial pinning centers. Using a picosecond laser exposure, a local modification of the HTS film were performed. The pulse energy varied from 300 to 4000 nJ, the pulse duration was 25 ps. A triangular array of micron size defects with a period of 50 μm was created. The dependences of the critical current and n-value change on the pulse energy were obtained. The parameters of the exposure resulting in an increase of the HTS tape critical current and tune of the I-V characteristic slope were found.

The formation of nanocrystal powders of Ln₂Zr₂O₇ (Ln=La - Tb) compounds upon calcinations up to 1500°C has been investigated by using of X-ray absorption fine structure spectroscopy combined with X-ray powder diffraction and Raman spectroscopy. It was found that the fluorite-pyrochlore phase transition occurs at calcination temperature in the range of 900-1200 °C (except Tb, T~1500 °C). The appearance of the ordered pyrochlore structure at calcination temperatures above 900 °C was fixed as an observation of superlattice peaks in diffraction and splitting of the first oxygen coordination shell in the local lanthanides environment in EXAFS and Raman spectra. In addition the scheme of fluorite-pyrochlore transition temperature dependence on radii of lanthanide cations was constructed.

Influence of synthesis conditions (type of atmosphere: reduction or oxidation, annealing temperature) on the chemical composition and structure of the compounds formed in the "HfO₂ - CeO₂/Ce₂O₃" system has been investigated by X-ray absorption fine structure spectroscopy combined with Raman spectroscopy, X-ray diffraction and thermogravimetric analysis. It was revealed that isothermal annealing of precursor at temperatures less than 1000°C in air leads to formation of Ce_0.5Hf_0.5O₂ powders with cubic fluorite-type structure (space group Fm-3m). Further increase of annealing temperatures above 1000°C causes decomposition of formed crystal structure into two phases: cubic and monoclinic. Annealing in reduction hydrogen atmosphere causes formation of Ce⁴⁺_2xCe³⁺_2-2xHf₂O_7+x compounds with intermediate oxidation state of cerium, where value of x depends on the reducing conditions and treatment parameters. Annealing in vacuum at 1400°C strongly reduces the content of Ce⁴⁺ in a powder samples and leads to formation of pyrochlore structure (space group Fd-3m) with predominant +3 oxidation state of cerium.

Influence of the concentration and type of rare-earth oxide on the chemical composition and structure of the compounds formed in the "Ln₂O₃-MO₂" system has been investigated by X-ray powder diffraction and Raman spectroscopy. It was found that crystallization temperature of synthesized powders rises with an increase in the concentration of Ln₂O₃. Besides, it was revealed that the efficiency of stabilization of high-temperature phases (tetragonal and cubic) in Ln₂O₃-ZrO₂ systems increases with the introduction of RE cations in the La³⁺ → Gd³⁺ → Y³⁺ series in accordance with the increase in the solubility of Ln₂O₃ in ZrO₂. A similar behavior was also observed for the Ln₂O₃-HfO₂ systems. Finally, we established that the compounds formed in Ln₂O₃-HfO₂ systems have a greater ability to crystallize in the monoclinic phase.

We have developed and implemented series of new original clamp high-pressure cells for neutron diffraction and inelastic neutron scattering at low temperatures. The cells design allows one to place them in the standard cryostats or cryomagnets used on neutron sources. Some results obtained for ZnCr2Se4 are demonstrated as an example.

Currently, the "Jülich Electric Dipole moment Investigations" (JEDI) collaboration, together with present EDM experiments at the COSY ring, is developing the conceptual design of a ring specifically for the search for the deuteron electric dipole moment (dEDM). One of the main problems in the EDM study is the spin precession in the vertical plane caused by the non-ideal positioning of accelerator elements through the magnetic dipole moment (MDM). The idea of how to separate the EDM from MDM is based on measuring the spin tune in different processes and comparing the results. The high precision of the spin tune measurement is achieved by collecting huge amounts of data. The JEDI collaboration aims at detecting the EDM at a level better than 10⁻²⁹e · cm, for which one requires a precision in the frequency estimate ∼ 10⁻⁹rad/sec. An estimate's statistical precision is conditional on the following factors: the total measurement time, determining the independent variable spread; measurement error; temporal modulation and spacing of sample points. In this paper we analyze the interplay between these factors, and estimate the best achievable precision under given conditions.

Electron-beam technologies of food products processing involves the use of modern packaging materials in form of polymer films of different composition. The objective of the research is to study the impact of accelerated electrons on the structure of the polymeric packaging materials used for storage of agricultural products. It was investigated radiation exposure on film material PE/PA (80/20) with a thickness of 80 mkm. This film used for storage of vegetables and fruits and has the necessary indicators for gas and vapor permeability. Electron beam treatment of the films was performed on a compact radiation sterilization installation with local bio-protection with electron energy of 5 MeV. A polymer films were irradiated with doses from 1 to 10 kGy. Changing the structure of the film composition was monitored by IR spectrometry. As a result of irradiation by accelerated electrons with doses up to 18 kGy is established that the polymer film is modification of the polymeric material in the form of a partial degradation with subsequent intra-molecular crosslinking. This improves the physico-mechanical properties in the transverse direction, and such film can be used for food packaging before electron-beam treatment.

To improve public security and prevent the diversion of radioactive material for Radiation Dispersion Devices, development of an inexpensive, portable, easy-to-manufacture linac system is very important. The bremsstrahlung X-rays produced by relativistic electron beam on a high-Z converter can mimic X-rays radiated from various radioactive sources. Here we consider development of two designs: one matching a Ir-192 source used in radiography with ∼1-1.3 MeV electrons, and another one Cs137 source using 3.5-4 MeV electrons that can be considered for borehole logging. Both designs use standing wave, high group velocity, cm- wave, accelerating structure. The logging tool conceptual design is based on KlyLac concept combining a klystron and linac operating in self-oscillating mode and sharing the same vacuum envelop, and electron beam.

Therapeutic hyperthermia (including RF hyperthermia) in combination with radiotherapy (called thermoradiotherapy) is one of widely used contemporary cancer treatment methods. The independent electron linac and RF system or their combinations are necessary for effective therapy. Whole-body hyperthermia is used for treatment of metastatic cancer that was spread throughout the body, regional one is used for treatment of part of the body (for instance leg or abdominal cavity). Local hyperthermia with characteristic size of heating volume of 20-100 mm permits to heat tumour without overheating of healthy tissues. The thermometry of deep suited tissues during the hyperthermia process is an important and complex task. Invasive methods as thermistors, optical sensors or thermo-couples can not be widely used because all of them are able to transport tumor cells to the healthy region of the patient body. Distant methods of the temperature measurement such, as radiothermometry and acoustic thermometry can not be used for tissues seated deeper than 5-7 cm. One of possible ways to solve the problem of temperature measurement of the deep suited tissues is discussed in this article: it was proposed to use the same electrodes for RF hyperthermia and thermometry. As known electrodynamics characteristics of tissues are sufficiently depends on temperature. It was proposed to use this effect for active radiothermometry in local hyperthermia. Two opposite RF dipoles can be used as generator and receiver of pick-up signal.

The dynamics of charged particles in a traveling wave field with the uniform - magnetic focusing has been studied. A Lagrange function for this motion is constructed and Lagrange equations describing geometrical and kinematic envelopes of the bunch are derived.

The results of RF optimizations for 324 MHz SC cross-bar H-mode (CH) cavity for 0.21 beta are presented. Maximum surface electric field of 36 MV/m and a corresponding effective accelerating gradient of 7 MV/m have been achieved.

The 800 MHz superconducting cavities with grooved beam pipes were suggested as one of the harmonic cavities design options for High Luminosity LHC project. Cavity simulations were carried out and scaled aluminium prototype having operational mode frequency of 2400 MHz was manufactured for testing the results of simulations. The experimental measurements of transverse shunt impedance with error estimation for higher order modes TM₁₁₀ and TE₁₁₁ for S-band elliptical cavity were done. The experiments using dielectric and metallic spherical beads and with ring probe were carried out. The Q-factor measurements for two-cell structure and array of two cells were carried out.

Electron dynamics in 6.5 MeV classic microtron of the Lebedev Physics Institute (LPI) is investigated by means of numerical methods. Particular emphasis is placed on the formation mechanism of electron bunches at the first circular orbits. An effect of microtron main parameters such as accelerating RF field amplitude, DC magnetic field, as well as a geometry and a position of a thermal emitter on characteristics of electron beam extracted from the microtron are studied. In the space of mentioned parameters a region corresponding an optimal microtron operation mode is found. It is noted that the unique geometric and energy characteristics of accelerated beam makes use of microtron attractive not only as injector into a synchrotron, but also as a driver in experiments on generation of coherent terahertz electromagnetic radiation.

Vacuum accelerating tube (AT) for neutron generation with the secondary electron emission suppressed by helical line pulse magnetic field which allocated inside accelerating gap in front of hollow conical cathodeis discussed. The central anode was covered by the hollow cathode. This technical solution of AT is an ion triode in which helical line serve as a grid. Computer simulation results of longitudinal magnetic field distributional along the axis are presented.

The paper is devoted to quasiperiodic intense beam dynamics is accelerating system. Particle interaction accounting is conducted with the use of well-known cloud-in-cell method. This numerical method is formalized, and mathematical model of space charge field intensity is suggested. Coulomb field intensity is presented in the form of integral over the domain of particle phase states. This permits beam evolution to be described by integro-differential equations. Controlled process quality is characterized by integral functional values. Beam dynamics optimization problem is formulated as trajectory ensemble control problem for dynamic system. Analytical expression of quality functional variation is obtained. It makes possible directed methods using for beam dynamics optimization.

When developing a particle accelerator for generating the high-precision beams, the injection system design is of importance, because it largely determines the output characteristics of the beam. At the present paper we consider the injection systems consisting of electrodes with given potentials. The design of such systems requires carrying out simulation of beam dynamics in the electrostatic fields. For external field simulation we use the new approach, proposed by A.D. Ovsyannikov, which is based on analytical approximations, or finite difference method, taking into account the real geometry of the injection system. The software designed for solving the problems of beam dynamics simulation and optimization in the injection system for non-relativistic beams has been developed. Both beam dynamics and electric field simulations in the injection system which use analytical approach and finite difference method have been made and the results presented in this paper.

For the multipactor discharge (MP) damping in the new CDS structure a method of forced excitation of high voltage oscillations in the coupling cell is proposed. It can be realized by application of an alternating frequency shift in the neighboring accelerating cells. For assured MP damping a control of both operating frequencies and the alternating frequency shift obtained is required. A method for determination of shifted frequencies in cells by the measurements in full setup (FS) and minimal setup (MS) of the structure was proposed. The substantiation of the technique arising from the equivalent circuits method and numerical simulations of the operating frequencies in FS and MS is presented.

The building of the radio frequency (RF) particle accelerator needs high-voltage pulsed modulator as a power supply for klystron or magnetron to feed the RF accelerating system. The development of a number of solid-state modulators for use in linear accelerators has allowed to develop a series of modular IGBT based compact solid-state modulators with different parameters. This series covers a wide range of needs in accelerator technology to feed a wide range of loads from the low power magnetrons to powerful klystrons. Each modulator of the series is built on base of a number of unified solid-state modules connected to the pulse transformer, and covers a wide range of modulators: voltage up to 250 kV, a peak current up to 250 A, average power up to 100 kW and the pulse duration up to 20 μsec. The parameters of the block with an overall dimensions 880×540×250 mm are: voltage 12 kV, peak current 1600 A, pulse duration 20 μsec, average power 10 kW with air-cooling and 40 kW with liquidcooling. These parameters do not represent a physical limit, and modulators to parameters outside these ranges can be created on request.

We propose a new design of a compact storage ring for a source of X-ray radiation on the basis of reverse Thomson scattering of laser radiation by electrons with the energy of 35–50 MeV, which has small number of optical elements and a significant clear space for the placement of a beam injection-extraction system and a RF cavity. The original laser cavity layout has been considered. The ring dynamic aperture after correction of chromaticity and a second-order dispersion function is sufficient for the injection and stable circulation of an electron bunch in the ring.

Positron emission tomography is modern nuclear medicine method used in metabolism and internals functions examinations. This method allows to diagnosticate treatments on their early stages. Mathematical algorithms are widely used not only for images reconstruction but also for PET data correction. In this paper random coincidences and scatter correction algorithms implementation are considered, as well as algorithm of PET projection data acquisition modeling for corrections verification.

Electron beam (EB) radiation technologies have been employed to increase efficiency of biologically active nanochips developed for agricultural plants seed pre-treatment with purpose of enhancing crop yield and productivity. Iron-containing nanoparticles (NPs), synthesized in reverse micelles following known radiation-chemical technique, have served as a multifunctional biologically active and phytosanitary substance of the chips. Porous chip carriers activation has been performed by EB ionization (doze 20kGy) of the active carbons (AC) prepared from agricultural waste and by-products: Jerusalem artichoke (Helianthus tuberosus) straw, rape (Brassica napus L. ssp. oleifera Metzg) straw, camelina (Camelina sativa (L.) Crantz) straw, wheat (Triticum aestivum) straw. Three methods, UV-VIS spectrophotometry, Electron Paramagnetic Resonance (EPR) spectroscopy, cyclic voltammetry (CV) have been used for process control and characterization of radiation-activated and NPs-modified ACs. The results show a notable effect of ACs activation by electron beam radiation, evidenced by FeNPs-adsorption capacity increase. Studies of the impact of Fe NPs-containing nanochip technology on enhancement of seeds germination rate and seedlings vigour suggest that reported electron beam radiation treatment techniques of the ACs from selected agricultural residues may be advantageous for industrial application.

This paper represents the results of modeling the electrodynamic characteristics (EDC) for a quarter-wave coaxial beam buncher, simulation of thermal loads of the buncher, modeling of the mechanical changes in the geometric parameters caused by the thermal load of the buncher and modeling of the new EDC depended on this changes.

This paper describes a superconducting L-band travelling wave cavity for electron linacs as an alternative to the 9-cell superconducting standing wave Tesla type cavity. A superconducting travelling wave cavity may provide 20-40% higher accelerating gradient by comparison with conventional cavities. This feature arises from an opportunity to use a smaller phase advance per cell which increases the transit time factor and affords the opportunity to use longer cavities because of its significantly smaller sensitivity to manufacturing errors. Two prototype superconducting travelling wave cavities were designed and manufactured for a high gradient travelling wave demonstration at cryogenic temperature. This paper presents the main milestones achieved towards this test.

The influence of microwave irradiation of mixtures on the strength of cement stone and concrete was studied. Created at NRNU MEPHI experimental installation for the investigation of microwave effects on imperfect dielectrics and semiconductor materials was the source of radiation. It is shown that on the twenty-eighth day after mixing, the strength of the cement stone increases by 1.2 times, and that of concrete by 2.2 times.

DAΦNE is the electron-positron collider operating at the energy of Φ-resonance, 1 GeV in the center of mass. The presently achieved luminosity is by about two orders of magnitude higher than that obtained at other colliders ever operated at this energy. Careful beam dynamic studies such as the vacuum chamber design with low beam coupling impedance, suppression of different kinds of beam instabilities, investigation of beam-beam interaction, optimization of the beam nonlinear motion have been the key ingredients that have helped to reach this impressive result. Many novel ideas in accelerator physics have been proposed and/or tested experimentally at DAΦNE for the first time. In this paper we discuss the advanced accelerator physics studies performed at DAΦNE.

The European XFEL (EXFEL) 1.3 GHz cavities were produced without any final cold RF performance guarantee for characteristics like accelerating gradient, quality factor or field emission. In the case of low-performance, DESY provided all re-treatment procedures in order to improve these characteristics getting closer to specification levels. But EXFEL cavities have very tight tolerances for the parameters like cavity length, cells eccentricity, fundamental mode frequency and field distribution on the operational mode. Usage of modern infrastructure, analytical methods and powerful tools of the database analysis allows us not only keeping these characteristics in specified ranges, but also investigate the cavity shape uncertainties and improve the damping of the higher order modes.

A new instrument was designed and implemented in order to increase the measurement accuracy of magnetic field maps for isochronous Cyclotrons manufactured by Advanced Cyclotron Systems Inc. This instrument uses the Hall Probe (HP) from New Zealand manufacturer Group3. The specific probe used is MPT-141 HP and can measure magnetic field in the range from 2G to 21kG. Use of a fast ADC NI9239 module and error reduction algorithms, based on a polynomial regression method, allowed to reduce the noise to 0.2G. The design of this instrument allows to measure high gradient magnetic fields, as the resolution of the HP arm angle is within 0.0005° and the radial position resolution is within 25μm. A set of National Instrument interfaces connected to a desktop computer through a network are used as base control and data acquisition systems.

The history of superconducting heavy ion accelerator ISAC-II started in 2000 with the development of niobium quarter wave cavities and cryomodules. The first stage of ISAC-II is in operation since 2006. In 2010 it was completed and made TRIUMF ISAC a leading ISOL facility supporting a full physics program with both stable and radioactive beams. TRIUMF is using its accumulated experience and resources for farther SRF development for ELINAC and external projects for VECC, RISP, FRIB and SLAC. Status of Superconducting ISAC-II accelerator and SRF development aspects, results and plans are discussed.

The design of industrial high average power traveling wave linacs must accurately consider some specific effects. For example, acceleration of high current beam reduces power flow in the accelerating waveguide. Space charge may influence the stability of longitudinal or transverse beam dynamics. Accurate treatment of beam loading is central to the design of high-power TW accelerators, and it is especially difficult to model in the meter-scale region where the electrons are nonrelativistic. Currently, there are two types of available codes: tracking codes (e.g. PARMELA or ASTRA) that cannot solve self-consistent problems, and particle-in-cell codes (e.g. Magic 3D or CST Particle Studio) that can model the physics correctly but are very time-consuming and resource-demanding. Hellweg is a special tool for quick and accurate electron dynamics simulation in traveling wave accelerating structures. The underlying theory of this software is based on the differential equations of motion. The effects considered in this code include beam loading, space charge forces, and external magnetic fields. We present the current capabilities of the code, provide benchmarking results, and discuss future plans. We also describe the browser-based GUI for executing Hellweg in the cloud.

This paper describes the techniques of production and trapping of thorium ions required to perform spectroscopic studies of thorium nuclear transition.

Distortions of the displacements measured by the heterodyne interferometer due to penetration of the electric excitation signal of the acousto-optic modulator into the path of registration and processing of optical signals are considered. The level of this type of noise is estimated and the ways of its elimination from data obtained using a three-coordinate heterodyne interferometer are proposed.

In the work the results of studies of thin-film samples of nanoclusters of tantalum and molybdenum metals on the surface of silicon dioxide SiO₂/Si (001) at room temperature are presented. The chemical composition and electronic structure of the obtained nanocluster films of Ta and Mo were controlled in situ by X-ray photoelectron spectroscopy (XPS). Susceptibility to oxidation during the exposure to the atmosphere of then nanocluster films, as well as their thermal stability when heated in a vacuum to 600 °C were studied ex situ by the XPS method. The size and shape of the nanoclusters composing the film were estimated ex situ by analyzing images obtained with a scanning electron microscope. The band structure before and after oxidation was studied by measuring the bandgap of the formed Ta and Mo films by the method of electron energy loss characteristic spectroscopy (REELS). Conclusions about thermoelectric properties of the formed nanocluster films of Ta and Mo were made.

The density of electronic states for bulk metals Au and Pd, their surfaces in the form of polycrystalline surface layers of nanometer thickness is investigated. The calculations were performed using density functional theory with pseudopotential in full relativistic approximation. Approximations have been found that provide calculations the density of electronic states of noble metal surfaces that describe the experimentally observed features of XPS spectra of the valence band of these metals.

Doppler cooling of thorium ions is described. The technique is to be applied for cooling of ions in a multisectional linear Paul trap for precise spectroscopy of ions and eventually detecting an isomeric nuclear transition.

The paper considersthe construction of a miniature radioisotope power unit based on thermoelectric conversion of thermal energy released during nuclear decay. It is proposed to use thin fluoropolymer films (membranes) as a dielectric heat-insulating material. The results of numerical simulation of a prototype of a miniature radioisotope thermoelectric battery unit based on the thorium-228 isotope in the ANSYS program are presented. The geometry of the system has been optimized. It was established that the temperature of the source can reach about 1033 K, and the efficiency of the considered battery unit can reach 16.8%, which corresponds to modern power supplies of this type.

Development of compact transportable frequency standards is an important goal of the modern applied physics. Despite of the great progress in the field of optical frequency standards with their ultimate accuracy and stability, they remain bulky, complex and sensitive systems. At the other hand, the best microwave frequency standards like cesium fountains are also bulky and sensitive to adjustments. Combination of techniques developed for optical and microwave standards can result in compact and robust transportable frequency standard. Here we suggest the microwave transition in ²⁵Mg⁺ laser cooled ion cloud for realization of highly accurate microwave frequency reference. We describe its design and experimental sequence, estimate its expected accuracy and stability.

We determine a lifetime of the 4/f¹³6s² (J = 5/2) clock level in ¹⁶⁹Tm atoms trapped in an optical lattice at 532 nm directly exciting a 1.14 μm magneto-dipole transition and measuring a decay rate from this level to the ground (J = 7/2) state. The measured lifetime of 112(4) ms corresponds to a transition spectral line width of 1.4 Hz which is in a good agreement with a theoretical prediction of 1.14 Hz.