High-Energy-Density Matter

Head of the group MHDE :

 

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HEDM Chair : Thomas Blenski

Our research is focused on the electronic properties of warm dense plasmas and involves theoretical and experimental studies on the emission and absorption of X and XUV radiation in such plasmas. We also develop new models of atoms in plasma and methods to calculate their equation of state (EOS).

The field is of both fundamental and applied character. Among fundamental problems is the physics of strongly coupled Coulomb systems . These problems are related to the description of atoms and of radiative phenomena in exotic states of mater. The physical conditions of matter that we investigate are common in inertial fusion facilities and in astrophysics, e.g., in stellar atmospheres (or in some nebulae).

Thus our work has important applications in the energy domain, especially in inertial fusion sciences — and it marginally applies to magnetic confinement fusion domain too. In the inertial fusion radiative phenomena often determine the energy transfer in fusion plasma. Both radiative opacities and EOS of dense plasmas are needed in order to model the inertial-confined-fusion scenarios.

In astrophysics the radiative transfer phenomena that we are studying define for instance the transition between the convective and the radiative transfer zone in stars, or the pulsation period of beta-cepheids stars.

Moreover, the plasmas we are studying provide interesting possibilities as light sources: X-ray laser, extreme-UV radiation (XUV), e.g., for nanolithography.

 

    

 

In order to validate the theoretical models, we perform measurement campaigns on large laser facilities, such as the series of opacity measurements performed at the LULI 2000 facility at Ecole Polytechnique.

 

The last experiments consisted in analyzing the X and XUV absorption of thin metallic targets heated and transformed into plasmas using an indirect drive scheme. Several diagnostics allow us to characterize the target conditions.

 

Another domain of activity, in the laboratory astrophysics domain, deals with the study of accretion shocks in forming stars.

Theoretical work involves sophisticated models taking into account the special thermodynamic conditions found in hot dense matter — high temperature and/or density, thermodynamic equilibrium or out-of-equilibrium physics — and the complexity of the ionic microscopic structure. The large number of charge states and of the relevant electronic configurations may require the use of a statistical description. However one must again resort to detailed atomic structure models when the line positions or the level populations must be accurately characterized.

 

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Last update : 09/27 2018 (720)

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