Publications

Soft X-ray shock loading and momentum coupling in meteorite and planetary materials

Remo, J.L.; Furnish, Michael D.; Lawrence, R.J.

X-ray momentum coupling coefficients, C M, were determined by measuring stress waveforms in planetary materials subjected to impulsive radiation loading from the SNL Z-machine. Targets were prepared from iron and stone meteorites, dunite (primarily magnesium rich olivine) in solid and powder forms (∼5 - 300 μm grains), and Si, Al, and Fe. All samples were ∼1 mm thick and, except for Si, backed by LiF single-crystal windows. The spectra of the incident x-rays included thermal radiation (blackbody 170 - 237 eV) and line emissions from the pinch material (Cu, Ni, Al, or stainless steel). Target fluences of 0.4 - 1.7 kJ/cm 2 at intensities 43 - 260 GW/cm 2 produced front surface plasma pressures of 2.6 - 12.4 GPa. Stress waves driven into the samples were attenuating due to the short ∼5 ns duration of the drive pulse. CM was determined using the fact that an attenuating wave impulse is constant, and accounted for the mechanical impedance mismatch between samples and window. Values ranged from 0.8 - 3.1 x 10 -5 s/m. CTH hydrocode modeling of x-ray coupling to porous and fully dense silica corroborated experimental results and extrapolations to other materials. © 2012 American Institute of Physics.