Electromagnetic generation of strong shocks in low pressure gas
Résumé
affiche P71 atelier 12 PNPS The interstellar medium (ISM) is a wide object of research, especially for the phenomena leading to the building up of protostellar objects, like mass accretion or outflows and jets. Accretion shocks are of particular interest as their radiative signature can be related to the rate of mass accretion onto the forming star. In recent years, laboratory plasma experiments have been developed to study radiative shocks relevant to astrophysics. These scaled models of accretion shocks have been successfully generated on high power lasers by launching a fast moving piston in a stationary gaseous medium. Complementary to experiments on lasers, pulsed power generators are also able to create astrophysically relevant shocks. On these facilities, high-intensity currents can produce magnetic fields of several Tesla which act as a piston, accelerating an annular plasma sheath and driving a strong shock in a tenuous gas. The results presented will describe the pulsed power setup and a lumped-parameter model, linking the transient discharge dynamics and quantities like mass and speed of the plasma sheath. The results of this 0-D model will be compared to 3-D MHD simulations performed with the code GORGON. This work has lead to an optimization process of the setup. The diagnostics which are currently implemented will be presented to illustrate the model as well as experimental records of the plasma speed. Work supported by DIM ACAV Île-de-France region, Labex PLAS@PAR (ANR-11-IDEX-0004-02), Observatoire de Paris-Meudon and UPMC university.