• N. M. Sakan

      Articles written in Journal of Astrophysics and Astronomy

    • Non-Elastic Processes in Atom Rydberg-Atom Collisions: Review of State of Art and Problems

      A. A. Mihajlov V. A. Srećković Lj. M. Ignjatović A. N. Klyucharev M. S. Dimitrijević N. M. Sakan

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      Inour previous research, it has been demonstrated that inelastic processes in atom Rydberg-atom collisions, such as chemi-ionization and ($n-n'$) mixing, should be considered together. Here we will review the present state-of-the-art and the actual problems. In this context, we will consider the influence of the ($n-n'$)-mixing during a symmetric atom Rydberg-atom collision processes on the intensity of chemi-ionization process. It will be taken into account H(1s) + H*(𝑛) collisional systems, where the principal quantum number is $n \gg 1$. It will be demonstrated that the inclusion of ($n-n'$) mixing in the calculation, influences significantly on the values of chemi-ionization rate coefficients, particularly in the lower part of the block of the Rydberg states. Different possible channels of the ($n-n'$)-mixing influence on chemi-ionization rate coefficients will be demonstrated. The possibility of interpretation of the ($n-n'$)-mixing influence will be considered on the basis of two existing methods for describing the inelastic processes in symmetrical atom Rydberg-atom collisions.

    • Inverse Bremsstrahlung in Astrophysical Plasmas: The Absorption Coefficients and Gaunt Factors

      A. A. Mihajlov V. A. Srećković N. M. Sakan

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      The electron–ion inverse Bremsstrahlung is considered here as a factor of the influence on the opacity of the different stellar atmospheres and other astrophysical plasmas. It is shown that this process can be successfully described in the frames of cut-off Coulomb potential model within the regions of the electron densities and temperatures. The relevant quantum mechanical method of the calculation of the corresponding spectral coefficient processes is described and discussed. The results obtained for the plasmas with the electron densities from 1014 cm$^{-3}$ to 2 · 1019 cm$^{−3}$ and temperatures from 5 · 103 K to 3 · 104 K in the wavelength region 100 nm < 𝜆 < 3000 nm are presented. Also, these results can be of interest for different laboratory plasmas.

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