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rencontre scientifique autour des processus radiatifs dans les plasmas (jeudi 3 juillet-15:30)

par Caroline CHAMPENOIS - publié le

Programme :

  • 15h30 : Accueil et discussions
  • 16h00 : séminaire "Photoprocesses in the field of ultra-short electromagnetic pulses". Dr Valery Astapenko Moscow Institute of Physics and Technology, Russia)
  • 16h45 : séminaire "Statistical theory of radiative processes in heavy atoms". Dr Valery Lisitsa (Kurchatov Institute, Moscow, Russia)

résumé 1 : Photoprocesses in the field of ultra-short electromagnetic pulses (USP)
- peculiarities of USP-matter interaction description : total probability in USP instead of the probability per unit time, Fourier transform of electric field strength instead of spectral radiation intensity ;
- derivation of general formula for total probability of photoprocesses in USP in terms of cross-section and electric field strength ;
- specific features of excitation and ionization of atoms by USP : dependence of pulse duration and carrier frequency of USP.

résumé 2 : Statistical theory of radiative processes in heavy atoms
The radiation properties of heavy elements in thermonuclear plasmas are of great present interest in connection with application of tungsten material for construction of divertor plates. The talk is devoted to calculations of tungsten radiative losses and tungsten spectra in modern thermonuclear installations including future thermonuclear reactor ITER. The problems are connected with extremely complex electronic structure of many electron tungsten ions. For the solution of the problems it was suggested statistical method of the radiative properties calculations. It makes it possible to express radiative losses and ion’s spectra in term of simple functionals from electron density distributions in atomic systems. Both models of Thomas-Fermi and Slater density distributions are used in calculations. The comparison with the results of more detail (Hartry-Fock types) theories demonstrates that the statistical theory has the same precisions as other more complicated codes. The results of statistical considerations are of principle physical interest, namely, they demonstrate the collective nature of electron motion in complex ions. It will be discussed in details the physical meaning of collective modes (plasmons) excitations in atomic rates and spectra.

contact pour cette rencontre ; Annette Calisti

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