Polozov group




Current term

2018


In 2018 we will host a few talks on spectroscopy, semi-conductors, condensed matter, accelerator science and more.
Seminar - 24th of June, 15:00 (Minsk time zone).
Raman Kudaktsin - "Radiation and thermal endurance of silicon photovoltaic structures processed with plasma beam"
ABSTRACT:
The main topic of the report is description of compression plasma flow (CPF), its purposes and perspectives. CPF is supersonic (50-100 km/s) flow of dense (up to 10^17 cm^-3) plasma (electron temperature is up to 10 eV). Plasma is accelerated under Ampere force and is compressed under action of self magnetic field (classic pinch effect). There are two main purposes of CPF usage. First is modification of surface layer of material. The main peculiarity here is that dense CPF not only melts material but also hydro-dynamically mixes this melted layer. Second is obtaining of clean plasma usable in thermonuclear applications. It was primary purpose of such flows as they allow to obtain very clean plasma.

PPT (In Russian)


Seminar - 3rd of May, 21:00 (Minsk time zone).
Mikalai Prakapenia - "Numerical scheme for treatment of Uehling-Uhlenbeck equation for binary and triple interactions in relativistic plasma and thermalization process"
ABSTRACT:
In this talk we discuss the calculation of the reaction rates of a relativistic electron-positron-photon plasma.

PPT


Seminar - 21st of February, 21:00 (Minsk time zone).
Darya Meniailava - "Simulation of optical cycles and spectral-energetic characteristics of electronic states for RbYb and CsYb molecules"
ABSTRACT:
In the frame of multi-reference perturbation theory method CASSCF/XMCQDPT2 taking into account the spin-orbit coupling the calculations of potential energy curves of the ground and low-lying excited electronic states of polar diatomic molecules RbYb and CsYb are presented. Molecular spectroscopic parameters of terms, transition dipole moments, Franck-Condon factors and vibronic energies are obtained. On the basis of the data obtained, the probabilities of two-step schemes (optical cycles) for the transfer of polar molecules RbYb and CsYb from highly excited vibrational states to the ground vibronic state are calculated. It is shown that the most effective optical cycles can be realized with the participation of the first excited sigma state.

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Past seminars

2017


Seminar - 21st of October, 21:00 (Minsk time zone).
Andrei Malinouski - "Evaluation of particle-scale radiative heat transfer in polydisperse beds"
ABSTRACT:
A new technique for implementing external (particle-to-wall) and particle-to-particle radiative heat transfer in discrete element method (DEM) simulations is proposed. It is based on view factor calculation. The idea behind the article is to find relevant local bed parameters, and establish relations between them and statistically averaged view factors. The proposed method shows better performance than alternatives currently used: it is more robust than transient direct calculation of instant view factors, but more accurate than simple averaging among neighbors. Both mono- and polydisperse mixtures of spherical particles were considered. It was shown that for dense beds simple linear dependence on particle to wall distance is valid for external radiative heat flux. Also, relation between relative particle size and its view factor to the wall was found for polydisperse beds. Exponential fit was proposed for particle-particle radiative heat flux estimation. The proposed correlations are valid for random dense packing of spherical particles; however, generalization for various bed porosities and particle shapes is straightforward. A DEM implementation of proposed relations is showcased using the simple example of external radiative heat-up of cylindrical particle bed.

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Seminar - 14th of August, 22:00 (Minsk time zone).
Vlad Stefanov - "International School of Atomic and Molecular Spectroscopy - Results"
ABSTRACT:
An overview of classes and talks at International School of Atomic and Molecular Spectroscopy 2017.

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Seminar - 8th of February, 19:00 (Minsk time zone).
Juliane Fonseca de Oliveira - "Bifurcation of Projected Patterns"
ABSTRACT:
This work is related to the study of pattern formation in symmetric physical systems. Our purpose is to discuss a possible model, namely the projection model, to explain the appearance and evolution of regular patterns in symmetric systems of equations. Results found in Crystallography and Equivariant Bifurcation Theory are used extensively in our work. In particular, we provide a formalism of how the model of projection can be used and interpreted to understand experiments of reaction-diffusion systems.

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