Density-dependent shock Hugoniot of polycrystalline diamond at pressures relevant to ICF

Abstract

In inertial confinement fusion (ICF), polycrystalline diamond—referred to as high density carbon (HDC)—has become a promising ablator candidate. However, with smaller grain size and lower initial density, the equation of state (EOS) for HDC can deviate from that for single-crystal diamond, which could be a concern for ICF designs, but current experimental EOS studies for HDC are far from sufficient to clarify how initial density affects target compressibility. Presented here are measurements of the Hugoniot for HDC with an initial density of 3.23 g/cm3 at pressures of 17–26 Mbar. Combined with experimental data reported for nanocrystalline diamond (NCD), a stiffer compressibility of NCD due to lower initial density is confirmed. Two porous models are used for comparison and seem to offer better agreement compared with SESAME databases. Also, the effect of temperature on the Grüneisen parameter, which is usually neglected, might need to be considered for NCD under these conditions. The present data offer important support for EOS studies relevant to ICF and constrain the construction of wide-range EOS.

Shock Hugoniot Data for Water up to 5 Mbar Obtained with Quartz Standard at High-Energy Laser Facilities

“…e impedance-matching method [5,[17][18][19]35] was used to estimate the shock state in water after passing the quartz/ water interface; an illustrative method is shown in Figure 3. Because of the impedance mismatch at the SiO 2 /H 2 O interface, the shock wave produced a transmitted shock into H 2 O and a reflected rarefaction wave propagating back into quartz.…”

“…e observation of large and asymmetric magnetic fields in these planets [2][3][4] indicated that the mantle is the origin of the field. As the dynamo theory requires the presence of a conductive material, it was suggested that one or all of the main ingredients of the mantle (ammonia, water, and methane, i.e., carbon [5,6]) experience a phase transition to a conducting state. Pioneering theoretical work has been done calculating the properties of the superionic phase of water at planetary conditions [7][8][9].…”

Sound Velocity Measurement of Shock-Compressed Quartz at Extreme Conditions

“…This confirms our sample was not preheated. The shock planar area from Al pusher is more than 500 µm from previous experiments' results [48][49][50][51]. Adjacent α-quartz samples were glued onto the back of Al pusher layer using an Sn thin film as epoxy glue layers < 1 µm thick.…”