Prof. Toshimori Sekine [HPSTAR]
Title: Shock compression science for pressures of 1 GPa to 5 TPa
Time: 14:00 - 15:00PM, Thursday, January 28th, 2021
Host: Yang Ding
Place: https://meeting.tencent.com/s/U2MVJ0wreIJA（Tencent Meeting, ID: 439 479 356）
Conference room A417, HPSTAR (Beijing)
Abstract:
In the seminar, I introduce the characteristics of shock wave and shock compression first to compare with the quasi-static compression used by many people in HPSTAR. We don’t need anvils, and we utilize the inertia to keep pressure for a limited time, independent upon the material strength. Shock compressed state is always released adiabatically, shortly after compressed. Then shock compression provides very unique process not only the compressed state but also the released state. Hypervelocity impact generates shock wave to form high-pressure phases in impact craters on the planet surfaces and meteorites that experienced impacts. The estimation of impact condition requires experimental results. We have three methods to characterize the shock effects. (1) sample recovery in which we investigate the post-shock samples, (2) in-situ measurements of shocked samples with time-resolved ways, and (3) numerical simulations. There are versatile applications, dependent upon the shock strength and shock wave generators, in condensed matter physics, Earth and planetary science, and materials science. Gas guns accelerate projectile to velocities of ~7 km/s corresponding to pressures of several 100s GPa, and lasers generates pressures of TPa range. We determine density and pressure through the Rankine-Hugoniot relations and temperature through the Planck equation. I will show some results including meteorite-impact formation of biomolecules and laser shocks coupled with X-ray free electron lasers (XFELs) that give us the structural information of shocked materials.
In the seminar, I introduce the characteristics of shock wave and shock compression first to compare with the quasi-static compression used by many people in HPSTAR. We don’t need anvils, and we utilize the inertia to keep pressure for a limited time, independent upon the material strength. Shock compressed state is always released adiabatically, shortly after compressed. Then shock compression provides very unique process not only the compressed state but also the released state. Hypervelocity impact generates shock wave to form high-pressure phases in impact craters on the planet surfaces and meteorites that experienced impacts. The estimation of impact condition requires experimental results. We have three methods to characterize the shock effects. (1) sample recovery in which we investigate the post-shock samples, (2) in-situ measurements of shocked samples with time-resolved ways, and (3) numerical simulations. There are versatile applications, dependent upon the shock strength and shock wave generators, in condensed matter physics, Earth and planetary science, and materials science. Gas guns accelerate projectile to velocities of ~7 km/s corresponding to pressures of several 100s GPa, and lasers generates pressures of TPa range. We determine density and pressure through the Rankine-Hugoniot relations and temperature through the Planck equation. I will show some results including meteorite-impact formation of biomolecules and laser shocks coupled with X-ray free electron lasers (XFELs) that give us the structural information of shocked materials.