Hugoniot Data for Carbon at Megabar Pressures

Abstract

We present an experimental point for the carbon equation of state (EOS) at megabar pressures, obtained by laser-driven shock waves. The rear side emissivity of "two-materials two-steps" targets (Al-C) was recorded with space and time resolution and, by applying the impedance mismatch method, allowed a direct determination of relative EOS points. Experiments were performed at the PALS and LULI laboratories using carbon samples with two different values of initial density, in order to explore a wider region of the phase diagram. Previously unreached pressures were obtained. The results are compared with previous experiments and with available theoretical models and seem to show a high compressibility of carbon at megabar pressures.

Development of x-ray radiography for high energy density physics

“…This is in contrast, for instance, with the results presented in Ref. 33. However, again, we repeat that the goal of the present work was more a "proof of principle" than a systematic study of EOS.…”

“…However, this method can in principle be used to complement those already described in literature, which have provided EOS data for an element like carbon, which is very important for astrophysical and planetological applications. 25,[31][32][33] Let us notice that x-ray radiography techniques have already been applied in the past to study the EOS of materials in the Megabar pressure range, first for the study of EOS of deuterium 34 and then for low-Z materials as plastics and beryllium. 35 In this cases, a ns x-ray backlighter was associated to a streak camera allowing following continuously the evolution of shock and fluid velocity in time, in a single laser shot.…”

Experiments and analysis of gold disk targets irradiated by smoothing beams of Xingguang II facilities with 350 nm wavelength

“…Shown in eqs. (9) and (17), the absorption efficiency nearly correlates with the limited flux parameter f. The factors influencing f include self-magnetic field, multi-group limited diffusion, non-local thermal electron transport and ion acoustic turbulence, etc. [4] .…”

“…Therefore, uniform irradiation is a necessary condition for ICF and propitious to increasing the compression of capsule, and can loosen the laser energy [8] . Moreover, the equation of state (EOS) research under direct drive requires uniform irradiation on the target surface [9,10] . Most theoretical and experimental investigations indicate that uniform irradiation can be dramatically improved through the beam smoothing technique [4,5,11] .…”

Hard x-ray radiography for density measurement in shock compressed matter

“…5 Despite their primary role, WDM EOS are difficult to model, mixing condensed matter and plasma physics. 7,[11][12][13] In this context, shock velocity is measured in the two materials, one of which is used as reference. In the last few years, several works 6-8 have demonstrated the validity of shock wave experiments as a tool for EOS studies.…”