{"id":1921,"date":"2021-07-13T12:30:32","date_gmt":"2021-07-13T10:30:32","guid":{"rendered":"http:\/\/172.24.24.16\/?page_id=1921"},"modified":"2021-08-21T14:04:35","modified_gmt":"2021-08-21T12:04:35","slug":"microscopic-processes-astrophysics-plasmas","status":"publish","type":"page","link":"http:\/\/www.lac.universite-paris-saclay.fr\/?page_id=1921&lang=en","title":{"rendered":"Microscopic processes: astrophysics, plasmas"},"content":{"rendered":"

Microscopic processes: astrophysics, plasmas<\/span><\/h2><\/div><\/div><\/div>\n\n
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\"altThe projects of this OR are declined according to two topics which are astrophysics and plasmas.\nplasmas.

\nAstrophysics<\/strong>:
\nThe project has mainly two parts. The first part will focus on the study of the scattering\ninelastic scattering with calculation (by a quantum time independent method) of energy exchanges\nbetween a target (a polar molecule) and a projectile (an atom or a simple molecule). Following the\nsuccesses of the last few years, this theme will be marked by a strong increase in the power of\nro-vibrational exchanges and a progressive disappearance of pure rotational exchanges. The ro-\nvibrational exchanges of water\/C 2 H 2 \/CH 4 \u2194 hydrogen or nitrogen molecules will be studied using the full power of the Jean-Zay\npower of the IDRIS Jean-Zay computer (converged nodes, CPU, GPU). The data produced by\nthese calculations will be compared with the experiment, in particular the infrared and\/or Raman spectroscopy\nwith application to exoplanets. This project is the object of a close collaboration with the LSMA (Tunis),\nand is part of an IRP 2021 application (not selected).

\nPlasmas<\/strong>
\nThe projects will be led by D. Benredjem and I. Schneider in two parts. The first\nconcerns the precise calculation of the rates that determine the properties of laboratory plasmas. In the\ncalculation of these rates, the effects of plasma density such as the screen effect and the lowering of the ionization potential\nionization potential will be taken into account. At high temperature, we will be interested in particular in the processes of\ncollision ionization and photoionization. At low temperature, we will explore the\n80recombination, excitation and dissociation of molecular cations in tokamak edge plasmas.\ntokamaks.
\nThe second part of the Plasmas project is motivated by the fact that accurate rates are\nThe second part of the Plasmas project is motivated by the fact that accurate rates are essential in the study of laser fusion plasmas, in particular in the calculation of the opacity of the capsule containing the DT\ncapsule containing the DT mixture. The opacity will be calculated in a non-equilibrium plasma\nequilibrium, which will require to solve a large number of coupled population equations.\ncoupled population equations. Indeed, we have shown in a recent work that the thermodynamic equilibrium approximation\nequilibrium does not always give a good account of the experimental results. Effects outside the thermodynamic\nthermodynamic equilibrium effects also appear in the on-board plasmas of controlled magnetic fusion reactors\nreactors, where the kinetics of D and T are strongly influenced by the presence of\n“impurities” containing Be, W, N, Ar, etc, whose role will be studied.<\/p>\n\n<\/div>

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