arXiv subjects

V. A. Sreckovic

Publications and source records attributed to V. A. Sreckovic.

25 records · Page 2Linked to original sources

arXiv2012

Rydberg atoms in astrophysics

Elementary processes in astrophysical phenomena traditionally attract researchers attention. At first this can be attributed to a group of hemi-ionization processes in Rydberg atom collisions with ground state parent atoms. This processes might be studied as a prototype of the elementary process of the radiation energy transformation into electrical one. The studies of nonlinear mechanics have shown that so called regime of dynamic chaos should be considered as typical, rather than exceptional situation in Rydberg atoms collision. From comparison of theory with experimental results it follows that a such kind of stochastic dynamic processes, occurred during the single collision, may be observed.

astro-ph.SR↗

arXiv2012

The self-consistent determination of HF electroconductivity of strongly coupled plasmas

Here is presented the calculation of the dynamic electrical conductivity of fully ionized, strongly coupled plasmas as a function of the external electric field frequency $ω$. The calculations are based on the the formula for the energy-dependent collision frequency which is determined by means of the Green function theory methods, as a sum over the Matsubara frequencies. The domain of extremely high electron density: $10^{21}\leq n_{e}\leq 10^{24} \textrm{cm}^{-3}$, and for the temperature varying from $10 \textrm{kK}$ to $1.000 \textrm{kK}$ was examined. The real and imaginary parts of the conductivity for every electron density are presented in the generalized Drude-like form as a two-parameter function of the frequency $ω$ in the region $0 < ω< 0.5ω_{p}$, where $ω_{p}$ is the plasma frequency. A good agreement between the obtained results and the existing theoretical and computing simulation data is shown.

physics.plasm-ph↗

arXiv2012

Electrical conductivity of plasmas of DB white dwarf atmospheres

The static electrical conductivity of non-ideal, dense, partially ionized helium plasma was calculated over a wide range of plasma parameters: temperatures $1\cdot 10^{4}\textrm{K} \lesssim T \lesssim 1\cdot 10^{5}\textrm{K}$ and mass density $1 \times 10^{-6} \textrm{g}/\textrm{cm}^{3} \lesssim ρ\lesssim 2 \textrm{g}/\textrm{cm}^{3}$. Calculations of electrical conductivity of plasma for the considered range of plasma parameters are of interest for DB white dwarf atmospheres with effective temperatures $1\cdot 10^{4}\textrm{K} \lesssim T_{eff} \lesssim 3\cdot 10^{4}\textrm{K}$. Electrical conductivity of plasma was calculated by using the modified random phase approximation and semiclassical method, adapted for the case of dense, partially ionized plasma. The results were compared with the unique existing experimental data, including the results related to the region of dense plasmas. In spite of low accuracy of the experimental data, the existing agreement with them indicates that results obtained in this paper are correct.

astro-ph.SR↗

arXiv2012

Modeling of continuous absorption of electromagnetic radiation in dense partially ionized plasmas

A new modeling way of describing the continuous absorption of electromagnetic (EM) radiation in dense partially ionized hydrogen plasma is tested in this work. It is shown that the obtained results give a possibility of calculating spectral absorption coefficients which characterize the relevant absorption processes in partially ionized hydrogen plasmas with electron densities $N_{e} \sim 10^{19}cm^{-3}$ and temperatures $T \approx 2\cdot 10^{4}K$. A key parameter of the used procedure is determined empirically. The calculation method is applied to wavelength region $300nm < λ< 500nm$. The presented results can be of interest for dense laboratory plasmas as well as for partially ionized layers of different stellar atmospheres.

astro-ph.SR↗

arXiv2012

The Chemi-Ionization Processes in Slow Collisions of Rydberg Atoms with Ground State Atoms: Mechanism and Applications

In this article the history and the current state of research of the chemiionization processes in atom-Rydberg atom collisions is presented. The principal assumptions of the model of such processes based on the dipole resonance mechanism, as well as the problems of stochastic ionization in atom-Rydberg atom collisions, are exposed. The properties of the collision kinetics in atom beams of various types used in contemporary experimentations are briefly described. Results of the calculation of the chemi-ionization rate coefficients are given and discussed for the range of the principal quantum number values 5 < n < 25. The role of the chemi-ionization processes in astrophysical and laboratory low-temperature plasmas, and the contemporary methods of their investigation are described. Also the directions of further research of chemi-ionization processes are discussed in this article.

physics.chem-ph↗

arXiv2012

The influence of solar spectral lines on electron concentration in terrestrial ionosphere

One of the methods of detection and analysis of solar flares is observing the time variations of certain solar spectral lines. During solar flares, a raise of electron concentration occurs in Earth's ionosphere which results in amplitude and phase variations of the recorded very low frequency (VLF) waves. We compared the data obtained by the analysis of recorded VLF signals and line spectra for different solar flares. In this paper we treated the DHO VLF signal transmitted from Germany at the frequency of 23.4 kHz recorded by the AWESOME system in Belgrade (Serbia) during solar flares in the period between 10:40 UT and 13:00 UT on 2011 April 22.

astro-ph.EP↗

arXiv2011

Modeling of the Continuous Absorption of Electromagnetic Radiation in Dense Hydrogen Plasma

In this work is examined a new modeling way of describing the continuous absorption of electromagnetic (EM) radiation in a dense partially ionized hydrogen plasmas with electron densities about $5\cdot10^{18}$ cm$^{-3}$ - $1.5\cdot10^{19}$cm$^{-3}$ and temperatures about $1.6 \cdot10^{4}$ K - $2.5 \cdot 10^{4}$ K in the wavelength region $300 \textrm{nm} < λ< 500 \textrm{nm}$. The obtained results can be applied to the plasmas of the partially ionized layers of different stellar atmospheres.

astro-ph.SR↗