Dynamic response of materials on subnanosecond time scales, and beryllium properties for inertial confinement fusion

Abstract

During the past few years, substantial progress has been made in developing experimental techniques capable of investigating the response of materials to dynamic loading on nanosecond time scales and shorter, with multiple diagnostics probing different aspects of the behavior. these relatively short time scales are scientifically interesting because plastic flow and phase changes in common materials with simple crystal structures -such as iron -may be suppressed, allowing unusual states to be induced and the dynamics of plasticity and polymorphism to be explored. Loading by laser ablation can be particularly convenient. The TRIDENT laser has been used to impart shocks and isentropic compression waves from ∼1 to 200 GPa in a range of elements and alloys, with diagnostics including surface velocimetry (line-imaging VISAR), surface displacement (framed area imaging), x-ray diffraction (single crystal and polycrystal), ellipsometry, and Raman spectroscopy. A major motivation has been the study of the properties of beryllium under conditions relevant to the fuel capsule in inertial confinement fusion: magnetically-driven shock and isentropic compression shots at Z were used to investigate the equation of state and shock melting characteristics, complemented by laser ablation experiments to investigate plasticity and heterogeneous response. These results will help to constrain acceptable tolerances on manufacturing, and possible loading paths, for inertial fusion ignition experiments at the National Ignition Facility. Laser-based techniques are being developed further for future material dynamics experiments, where it should be possible to obtain high quality data on strength and phase changes up to at least 1 TPa.

Diagnosis of MBAR Laser Produced Shocks in Tin Using Short Pulse Probes

“…More work N/A N/A N/A must be done before any conclusions can be drawn from this data, and before it can be compared to Ref. [3].…”

“…One method to study the behavior of materials under these conditions is to drive a strong shock wave through a material and watch its response. In many cases the material response is complicated by phase transitions such as lattice restructuring [1][2][3] and melting [1,[3][4][5][6].…”

Numerical solution of shock and ramp compression for general material properties

“…However, the flow stress has been observed to be much higher on nanosecond time scales, 25 and interactions between elastic and plastic waves may have a significant effect on the compression and wave propagation. However, the flow stress has been observed to be much higher on nanosecond time scales, 25 and interactions between elastic and plastic waves may have a significant effect on the compression and wave propagation.…”

An investigation progress toward Be-based ablator materials for the inertial confinement fusion

“…The Be capsule fabricated by anyone or any method is always characterized by a columnar grain with large diameter [33][34][35][36][37] , which is relevant closely to a hcp structure of Be. The lattice constant, a = 0.2286 nm, c = 0.3584 nm, and the ratio c to a is 1.568, which is the lowest in all metals with hcp structure.…”