Shock-wave physics experiments with high-power proton beams

Abstract

At the Karlsruhe Light Ion Facility (KALIF) high-power proton beams with power densities up to ∼ 1 TW/cm2 are generated depositing up to 40 kJ of ion energy in a focal spot of 6∼8-mm diameter. With peak proton energies of ∼ 1.7 MeV, specific power densities of up to 200 TW/g and energy densities of several MJ/g can be realized. This is a regime in which experiments providing information on the equation of state (EOS), dynamics of the beam interaction with condensed targets, and properties of solids and plasma at high-energy densities are of particular interest. In the present paper we report on shock-wave experiments using solid targets and high-resolution laser-Doppler velocimetry. The empirical data provided are used to verify code simulations and the used EOS-data in these calculations, to investigate the beam-target interaction, and to perform series of shock-wave measurements of properties of different materials. The ∼40-ns FWHM proton beam can be used to generate, by material ablation or impact of ablatively accelerated flyers, intense shock waves, permitting the investigation of shock compressibility, dynamic failure of solids under nanosecond load duration, phase transitions, and viscosity at strain rates up to ∼108 s-1. Recently an improved line-imaging velocimeter was set up to measure the spatial velocity variation with a maximum resolution of < 10 μm, opening the possibility to address new issues like growth of instabilities or local dynamics of the spall fracture.