Heat capacities Cv, Cp, and sound velocity W of carbon dioxide are calculated on the basis of a new thermal combined equation of state (EoS) with a low number of regulated constants. This equation includes a new regular EoS with 11 coefficients, a scaling EoS with six coefficients, and a regular transition function containing two adjustable parameters. Calculating results for thermodynamic properties of CO2 in the regular behavior range of up to 200 MPa correspond to the accuracy level of modern practical equations of state with large numbers of determined constants. This makes it possible to calculate the properties of CO2 in the critical region, taking into account the achievements of scaling theory. To determine the constants of the calculated equations, only p,ρ,T-data for CO2 were used. The experimental and tabular data on Cv, Cp, S, H, and W were not involved except isochoric heat capacity Cv in the ideal gas state. These data were used to compare the calculated results with the experimental and tabulated values. The universal critical exponents were taken in accordance with the three-dimensional Ising model. The average errors in describing the thermal properties of CO2 do not exceed errors: rms error is 0.93 % in pressure and max deviation in Cv is 10 %. Divergences in the critical region relate to application of the scaling equation of state, in contrast to the regular equations. The comparison was made with calculated Cv, Cp using the current crossover EoSs for CO2.

A low-parametric equation for calculating the CH4 viscosity coefficient in liquid, gaseous, and fluid states was derived using previously obtained unambiguous dependence of the "excess" viscosity of liquids and dense gases on the density of internal energy. The equation describes the viscosity of methane at the temperatures from 91 K to 620 K and pressures of up to 50 MPa in the limits of experimental error.

A new fundamental low-parametric equation of state in the form of a reduced Helmholtz function is developed for carbon dioxide to describe the thermodynamic properties of normal substances. The equation of state makes it possible to describe the thermal and caloric properties of a gas, liquid, or supercritical fluid in the range of pressures up to 200 MPa with high accuracy that is close to experimental (except in the critical region). Carbon dioxide’s caloric properties and speed of sound in it are calculated without using any caloric data, except for the ideal gas enthalpy. The calculated values of the isochoric heat capacity, speed of sound, and other thermodynamic properties are in good agreement with experimental data (reliable reference tables).

Optical parametric oscillator based on Russian domestic PPKTP structure was created. High quality KTP crystals, of resistivity as high as similar to 10(13) Ohm*cm and coercive electric field as low as 2,3 kV/mm weregrownat Crystals of Siberia Ltd.,and 1.8 mm-thick substrates were processed at Labfer Ltd.

A low-parametric equation for calculating the SFe viscosity coefficient in liquid, gaseous, and fluid states was derived using previously obtained unambiguous dependence of the “excess” viscosity of liquids and dense gases on the density of internal energy. The equation describes the viscosity of sulfur hexafluoride at the temperatures from 230 K to 650 K and pressures of up to 50 MPa in the limits of experimental error.

Dispersion of refractive index and absorption coefficients in flux-grown high-resistivity KTiOPO4 crystals between 0.2-2.5 THz are verified at room temperature by a THz-TDS. Measured dispersion components n(x), n(y) and n(z), are approximated for the first time in the form of Sellmeier equations. Phase matching for down-conversion into the THz range under a visible and near IR pump is found possible only in the principle XZ plane by s - f -> f and s - f -> s types of three-wave interactions. Low frequency THz generation is favorable due to the low absorption coefficient down to 0.2 cm(-1), below 0.5 THz.

To describe the thermodynamic properties of xenon, a new fundamental low-parametric equation of state (in the form of reduced Helmholtz energy) is obtained with the help of the methods and approaches developed by the authors. It allows us to describe the thermal properties of gas, liquid, and fluid with a sufficiently high accuracy close to the accuracy of experiment in a range from the density in the ideal gas state to the density at the triple point, excluding the critical region. The caloric properties and speed of xenon sound are calculated without involving any caloric data, with the exception of ideal gas enthalpy. The values of isobaric heat capacity, sound speed, and other thermodynamic properties obtained by calculations are in good agreement with the experimental data.

Heat capacities Cv, Cp and sound velocity W of carbon dioxide are calculated basing on the new thermal equation of state (EoS) with a small number of regulated constants. This equation includes a new regular EoS with 11 coefficients and scaling EoS with six coefficients and regular transition function containing two adjustable parameters. The results of calculating the thermodynamic properties of CO2 in the regular behavior range of up to 200 MPa correspond to the accuracy level of the modern reference equations of state. To determine the constants of the calculated equations, only p,ρ,T -data for CO2 were used. The average error in describing the thermal properties of CO2 does not exceed the error of the available experimental data. The calculated values coincide with the values of the reference data.

Using the previously obtained dependence of excess viscosity on internal energy density and low-parametric unified equation of state for calculation of thermodynamic properties of liquid, gas, and fluid, the equation for the excess viscosity of argon in the range of the “mixed” mechanism of momentum transfer in the shear flow was derived. Different versions of approximation of excess viscosity dependence on the density of interaction energy were compared, and the optimal version of this dependence was determined. A simple unified low-parametric equation was obtained for describing the coefficient of argon viscosity in a wide range of state parameters. It is shown that the proposed low-parametric equation for calculating the viscosity coefficient of liquid and gas allows reliable extrapolation beyond the studied region.

A new fundamental low-parametric equation of state in the form of reduced Helmholtz function for describing thermodynamic properties of normal substances was obtained using the methods and approaches developed earlier by the authors. It allows us to describe the thermal properties of gas, liquid, and fluid in the range from the density in ideal-gas state to the density at a triple point (except the critical region) with sufficiently high accuracy close to the accuracy of experiment. The caloric properties and sound velocity of argon, nitrogen, and carbon dioxide are calculated without involving any caloric data, except the ideal gas enthalpy. The obtained values of isochoric heat capacity, sound velocity, and other thermodynamic properties are in good agreement with experimental (reliable tabular) data.

Specific heats C v and C p, entropy S, enthalpy H, and speed of sound W have been calculated using a new thermal equation of state with a small number of variable constants, which includes regular and scale contributions with a new transition function. The calculation results correspond to the accuracy level of the modern reference equations of state with a large number of determined parameters in the regular behavioral region of SF6 properties; in the critical region, these results make it possible to supplement the existing reference data with the related tables, taking into account the scaling-theory advances. The experimental and tabular data on C v, C p, S, H, and W have not been used to determine the constants of the calculation equations (except for isochoric specific heat, C v, in the ideal-gas state). These data have been applied only for comparison of the calculated values with the experimental and tabular values. To calculate the behavior of thermal properties in the critical region, universal critical indices α, β, and γ have been used according to the threedimensional Ising model. The mean error in describing thermal properties of SF6 does not exceed the error of the existing experimental data. The calculated values coincide with the modern reference data in the regular region in the entire range of gas and liquid states. The discrepancies in the critical region are due to the application of the scale equation of state (in contrast to the regular equations used previously in this region for composing reference tables).

A new unified combined equation of the state of liquid, gas, and fluid with a small number of adjustable constants is considered. Using this equation, tables of sulfur hexafluoride SF6 thermodynamic properties are compiled and proposed as standard reference data. The equation of state has the form of an explicit dependence of p = p(ρ, T) and does the following: transfers the thermal and caloric properties of SF6 in the regular component of the thermodynamic surface with the accuracy of the experiment; includes critical exponents β, α, and γ, taken in agreement with the three-dimensional Ising model; and corresponds to the relations of thermodynamics and the scale theory for properties in the critical region. The adjustable constants are obtained by approximating the p,ρ,T-data of SF6 using a combined equation of state in the ranges of 224 ≤ T ≤ 623 K, 0.1 ≤ p ≤ 30 MPa, and 8 ≤ ρ ≤ 1842 kg/m3. It includes a new regular component for approximating p,ρ,T-data in the liquid and gas regions of states outside the critical region, four of the 13 constants that are determined by the conditions at the critical and triple points, the singular component that is a scale equation (six constants) in explicit form for the critical region, and a new crossover function for combining these equations. The total number of system-dependent constants is 21, including parameters of the critical point. The root-mean-square error in the description of p,ρ,T-data of SF6 by pressure is 1.05% in the entire range of gas and liquid states; the average absolute deviation is 0.51%.

Experimental diagrams of binary systems, including compounds that melt upon decomposition, sometimes display the metastable congruent melting of such compounds above the peritectic equilibrium temperature. Conditions in which the occurrence of superheated states of binary systems is possible are analyzed. Thermodynamic and kinetic interpretations of such phenomena are presented.

Using the earlier proposed relations for the viscosity coefficient and internal energy of a thermodynamic system, a simple unified few-parameter equation for describing the viscosity coefficient of argon, nitrogen, and carbon dioxide in a wide range of the state parameters has been derived.

A miniature intracavity KTP-based electro-optic phase modulator has been developed which can be used for effective stabilisation of an optical frequency comb of a femtosecond erbium-doped fibre laser to an optical frequency standard. The use of such an electro-optic modulator (EOM) has made it possible to extend the working frequency band of a phase-locked loop system for laser stabilisation to several hundred kilohertz. We demonstrate that the KTP-based EOM is sufficiently sensitive even at a small optical length, which allows it to be readily integrated into cavities of femtosecond fibre lasers with high mode frequency spacings (over ).