V. P. Demkin

Spectroscopic studies of non-thermal plasma jet at atmospheric pressure formed in low-current nonsteady-state plasmatron for biomedical applications

The optical and electrophysical characteristics of the nonequilibrium low-temperature plasma formed by a low-current nonsteady-state plasmatron are experimentally investigated in the present work. It is demonstrated that experimental data on the optical diagnostics of the plasma jet can provide a basis for the construction of a self-consistent physical and mathematical plasma model and for the creation of plasma sources with controllable electrophysical parameters intended for the generation of the required concentration of active particles. Results of spectroscopic diagnostics of plasma of the low-current nonsteady-state plasmatron confirm that the given source is efficient for the generation of charged particles and short-wavelength radiation—important plasma components for biomedical problems of an increase in the efficiency of treatment of biological tissues by charged particles. Measurement of the spatial distribution of the plasma jet potential by the probe method has demonstrated that a negative sp...

Pathogenetic Role of Endothelial Dysfunction in Idiopathic Vestibulopathy

Comparative analysis of the groups of patients with idiopathic bilateral vestibular hypofunction and a group of vestibulopathy patients with vertebrobasilar insufficiency demonstrated identity of the basic and additional diagnostic parameters in these syndromes as well as similarity in clinical diagnostic and anamnesis data. In all cases, functional assessment of endothelium-dependent vasodilation and selected biochemical marker sICAM-1 revealed endothelial dysfunction. Drug correction of endothelial dysfunction positively affected the manifestations of major and minor features of the syndrome, which confirmed the contribution of endothelial functional disturbances to the pathogenesis of bilateral vestibular hypofunction.

AMPLITUDE-DISTORTION FACTORS FOR THE INELASTIC SCATTERING OF AN ELECTRON AT A NEON ATOM IN AN ELECTRIC FIELD

Inelastic electron scattering at a neon atom in the presence of an external electric field is considered. The distortion factors of the cross sectionηγM(F) are calculated for a series of 4d and 5d levels. It is shown that the distortion factor in strong fields is a nonlinear and nonmonotonic function of the field. The distortion factors and transition probabilitiesAγγ′, are compared. The correlation between the behavior ofAγγ′, andηγM(F) is explained by the dependence of the mean dipole moment of the Stark state on the field strength.

Calculation of the differential cross sections of excitation and ionization of a helium atom by electrons

Equations for the amplitudes and differential cross sections of electronic excitation and ionization of a helium atom are derived in the approximation of a “frozen” ion core. The wave functions of the discrete states are chosen in the form of generalized hydrogenlike orbitals. The radial wave functions of the continuous spectrum are determined by solving the equation of motion numerically. The differential excitation cross sections of excitation of the 2p, 3p, and 4p levels and ionization of a helium atom by electrons are calculated in the energy range up to 50 eV. Estimates are obtained for the nonorthogonal wave functions in the amplitudes of the excitation and ionization processes. It is shown that the given method is more compatible with experiment than the Born method.

Inelastic collisions of electrons with atoms in an electric field

Formulas have been obtained in the Bethe—Born approximation for the excitation cross section of atoms by electrons in a constant electric field. The influence of the electric field is reduced to the accumulation of momentum by the incident electron and the variation of the electronic configuration of the atom. The collision cross section is in the form of two components dσ⊥ and dσ¦, which correspond to collisions with transfers of the momentum components to the perpendicular and parallel electric field. The angular dependence of the cross section is determined by the anisotropy coefficients ηtT andη¦. In the general case these coefficients depend on the polar and azimuthal angles θ and ϕ.

Transition probabilities of neon atom in a constant electric field

The probability of 5s-3d, 5s-3p, 5p-3s, 5d-3s, 4d-3p, and 4f-3p transitions of Ne I in an electric field is calculated. It is shown that the probability of the permitted transitions 5s-3p and 5p-3s is unchanged with increase in the field from 0 to 50 kV/cm, while the probability of the forbidden transitions 5s-3d and 5d-3s is very small. In the given range of field strengths, the probability of permitted 4d-3p transitions markedly falls and intense forbidden 4f-3p transitions appear. Of the configurations considered, the electric field has most effect on those withι⩾2.

Calculation of the quadratic stark effect in krypton

The quadratic Stark effect for the seventeen levels of krypton in the 4s2p5ns-, 4s2p5np- and 4s2p5nd -configurations is calculated in the Coulomb approximation. The calculation is conducted for j-l and j-j coupling. The results obtained are found to agree satisfactorily with experiment. The Stark effect constants are given.