Link do spotkania w aplikacji Microsoft Teams: https://teams.microsoft.com/meet/393930235177432?p=mZyvyH2EOBW1EuPpzC

Identyfikator spotkania: 393 930 235 177 432

Kod dostępu: Ey7Uk3eE

Abstract

The interest in the behavior of boron nitride (BN) in extreme conditions is largely justified by recent renaissance in hydrogen boron fusion studies and by the perspective of application of this material as ablator in ICF in alternative to diamond (high density carbon, HDC). In both cases, hydro simulations need information on the Equation of State (EoS) of boron and boron compounds. The database of experimental EoS points for boron compounds in extreme conditions is very limited. Before our work, only a few points were available on BN between 12 and 27 Mbars and only one point at 56 Mbars for pure boron. We conducted studies of the BN EoS at the ELI BL, GEKKO, PALS and SGIII-p laser installations. Several EoS points along the Hugoniot curve were obtained for both h-BN and c-BN at pressures up to ~18 Mbar. While the experiment at SGIII-p used an indirect drive approach, the others were based on direct-drive illumination of the target. Lasers were operating either at 2w or 3w with pulse length τL from ∼ 350 ps up to 4 ns, energies up to 470 J in direct drive approach and up to 6400 J in indirect drive approach. A flat-top intensity profile within the focal spot of ~350- 600 μm diameter was assured by using a phase plate. The experimental points were obtained using standard diagnostics: Streaked Optical Pyrometry (SOP) and Velocity Interferometer System for Any Reflector (VISAR). We then simultaneously measured the shock velocities in the reference material and in BN, and we used the impedance mismatch technique to obtain the experimental EoS points of BN, which resultes in fair agreement with the available theoretical models. In the experiment, we used multilayer stepped targets produced at Scitech Precision, UK, and targets produced by LFRC and HPSTAR in China, with either aluminum or quartz as reference material.