Radiation Hydrodynamics Scaling Laws in High Energy Density Physics and Laboratory Astrophysics

accepted paperInternational audienceIn this paper, radiating fluids scaling laws are studied. We focus on optically thin and optically thick regimes which are relevant for both astrophysics and laboratory experiments. By using homothetic Lie groups, we obtain the scaling laws, the similarity properties and the number of free parameters which allow to rescale experiments in the two astrophyscial situations

Analytical solutions of specific classes of astrophysical radiating shocks

In this paper we study specific classes of radiating shocks which are widely spread in astrophysical environments. We present more general solutions of their structure and proceed to the analytical determination of physical quantities

Scaling laws for radiating fluids: the pillar of laboratory astrophysics

International audienceIn this paper, we derive the scaling laws for different radiating fluids. The studied regimes are relevant for both laboratory astrophysics and High Energy Density Physics. Using Lie groups theory, we obtain scaling laws, the similarity properties and the number of free parameters to rescale experiments

Invariance concepts and scalability of two-temperature astrophysical radiating fluids

International audienceIn this work, we present a classification of laboratory astrophysics experiments. We introduce different invariance concepts in order to build scaling laws and to determine the astrophysical relevant of laboratory experiments. Finally we present an analysis of the two-temperature radiating fluid scalability

Numerical modeling of accretion column in polars

International audienceUsing powerful lasers, we are now able to produce in laboratory relevant regimes of density, temperature and velocity to create a diagnosable exact scaled model of magnetic cataclysmic variables accretion column. We present here preliminary results of a numerical modeling of these astrophysical objects which will allow us to precise the experimental setup of future experiments

Theoretical and numerical studies of the Vishniac instability in supernova remnants

International audienceVishniac instability has been theoretically studied in supernova remnants where it is supposed to explain the fragmentation of the interstellar medium. However its role is not fully demonstrated in these astrophysical objects. Conditions and assumptions required for the instability growth are explained in detail in the present paper. In addition the HYDRO-MUSCL hydrodynamic code has been used to simulate this instability in order to compare the numerical growth rate with the Vishniac analytical solution

From lasers to the universe: Scaling laws in laboratory astrophysics

International audienceIn this work scaling laws in laboratory astrophysics are studied. It is shown that mathematical models governing radiation hydrodynamics-driven phenomena are invariant under the homothetic group transformation and can be rescaled according to several types of scaling laws. This property is valid for both optically thick and optically thin materials and it allows a correct and rigorous connection between astrophysical objects or phenomena and laboratory experiments. This approach is applied to astrophysical jets and radiative shocks where advantages as well as difficulties are pointed out

Analytical structure of steady radiative shocks in magnetic cataclysmic variables

International audienceIn this paper we study specific classes of radiating shocks which are widely spread in astrophysical environments. We present new analytical solutions available for any exponents of typical power-law cooling function which generalize the five special cases (corresponding to specific values of these exponents) of radiating shocks structure and proceed to the analytical determination of physical quantities. Then an application of the results for the accretion shock in polar is realized. A discussion of the reproducibility of cooling layer in laboratory is proposed using scaling laws

Classification of and recent research involving radiative shocks

International audienceRadiative shocks (RS) occur in astrophysical systems and in high-energy density laboratory experiments. Aided by three dimensionless parameters, we propose a classification of RS into four types, integrating previous work that has focused independently on optical depth and on Mach number. Specific terms, such as a cooling function, a radiative flux, or radiative energy and pressure must be added to the Euler equations in order to model these various kinds of shocks. We examine how these terms correspond to the radiative classification regimes. In astrophysics, observed RS arise generally in optically thin material. Thus, radiation escapes without interaction with the surrounding gas, except perhaps to ionize it, and the energy loss in such shocks can be modeled by a cooling function Lambda. In this case only the post-shock region is structured by the radiation cooling. We found the analytical solution for hydrodynamic equations including Lambda ∝ rho ε P zeta x theta for arbitrary values of ε, zeta, theta. This is a completely new result. An application of this calculation for the accretion shock in cataclysmic variables of polar type is given in astrophysical terms. We also draw a parallel between RS experiments performed using the LULI2000 laser facility, in France and the Omega laser Facility, in USA. RS developed in these laboratories are more or less optically thick. These high-Mach number RS present a radiative precursor

Astrophysical outflows simulated by laser-driven plasma jets

International audienceWithin the framework of laboratory astrophysics, we form a qualified multidisciplinary group in radiative hydrodynamics. Since 10 years, we have developed laboratory experiments as radiative shocks and plasma jets in connection to astrophysics. Such laboratory experiments provide a unique opportunity to validate models and numerical schemes introduced in radiative hydrodynamics codes. Here we summarize our experimental researches about plasma jets. Laboratory astrophysical experiments have been performed using LULI2000 (France), VULCAN (UK) and GEKKO XII (Japan) intense lasers. The goal of these experiments is to investigate some of the complex features of jets from Young Stellar Objects (YSO), and in particular its interaction with the interstellar medium (ISM)