The behavior of diamond under extreme pressure conditions is crucial for the advancement of inertial confinement fusion (ICF) and high-energy-density physics. While synthetic nanocrystalline diamond, or high-density carbon (HDC), has played a key role in achieving ICF ignition [1,2], significant uncertainties remain regarding the impact of crystalline orientation and amorphous structures on shock Hugoniot behavior and melting dynamics. This study aims to clarify the orientation-dependent equation of state (EoS) of single-crystal diamond and compare it to the shock properties of amorphous diamond.
Our research involves experiments conducted on <110> oriented single-crystal diamond and amorphous diamond with a density of approximately 3.2 g/cc. Using decaying shock techniques [3], we trace the complete pressure-temperature (P-T) Hugoniot trajectory. By analyzing the temperature evolution and phase boundaries of different orientations and amorphous structures, we explore the melting landscape and structural stability under dynamic compression. The experiments, performed at the SG III P laser facility, utilize indirect-driven shocks with a planar hohlraum drive and ultrafast VISAR-SOP diagnostics. These results aim to clarify how crystalline anisotropy and amorphous structure affect shock-induced melting, offering essential benchmarks for molecular dynamics models and enhancing the performance of HDC ablators in ICF applications [4,5].
This work significantly advances the understanding of diamond's high-pressure phase diagram, addressing discrepancies observed between nanocrystalline and single-crystal behaviors. By correlating orientation-dependent shock physics with ablator performance, the findings aim to guide the design of next-generation ICF capsules and the synthesis of metastable materials.
[1] A. B. Zylstra et al., Phys. Rev. Lett. 126 , 025001 (2021).
[2] D. D.-M. Ho et al., J. Phys.: Conf. Ser. 717 , 012023 (2016).
[3] Liang Sun and T. Sekine, Proc. ICMRE 2023 (2023).
[4] Peng Wang et al., Matter Radiat. Extremes 6 , 035902 (2021).
[5] K. Jakubowska et al., High Power Laser Sci. Eng. 9 , e3 (2021).
 

laser shock compression,ICF,Molecular dynamics; melting temperature; free energy,ablator