Investigating the pressure wave generated across a solid target as the result of the impact of a pulsed multi-MeV electron beam

ASTERIX is a Marx generator operated at the CEA Gramat that excites an electron diode with a maximum voltage of 6.4 MV, and a current of about 100 kA with a 45 ns full width at half maximum. The electron beam emitted from the cathode interacts with an aluminum-backed tantalum anode target, resulting in high x-ray pulse generation efficiency. In order to complement the set of diagnostics used for characterizing the plasma generated on the target surface upon the incidence of this high flux multi-Mev electron beam, a Doppler laser interferometer was used to measure the velocity of the target back surface. A series of experiments were performed with a 230 mm tantalum target backed with various thicknesses of Aluminum layer. The experimental surface velocity profiles were compared to simulated velocity profiles obtained using a Lagrangian hydrodynamic code. The latter used tabulated energy deposition source term inferred from calculated electron fluence on the anode, as an input. We show that back surface velocity measurements can be related to spectroscopic measurements obtained previously in order to characterize the source term.