The elastic-plastic response of aluminum films to ultrafast laser-generated shocks

Abstract

We present the free surface response of 2, 5, and 8 m aluminum films to shocks generated from chirped ultrafast lasers. We find two distinct steps to the measured free surface velocity that indicate a separation of the faster elastic wave from the slower plastic wave. We resolve the separation of the two waves to times as short as 20 ps. We measured peak elastic free surface velocities as high as 1.4 km/s corresponding to elastic stresses of 12 GPa. The elastic waves rapidly decay with increasing sample thickness. The magnitude of both the elastic wave and the plastic wave and the temporal separation between them was strongly dependent on the incident laser drive energy.

Single two-zone elastic-plastic shock waves in solids

“…Such anomalously-high elastic wave amplitudes were actually observed in recent laser-driven experiments [12][13][14], thus implicitly confirming the existence of the two-zone regime. In particular, a leading elastic wave of 150 nm thickness and pressure 12 GPa was detected in experiments by Whitley et al [12]. The visible attenuation of the elastic wave during wave propagation, i.e.…”

“…Therefore, it is quite natural to assume that there is a substantial portion of the SW front containing the material in an elastic metastable state at a applied pressure greater than that at the HEL. Indeed, longitudinal elastic pressures higher than P HEL ∼ 0.3 GPa [3][4][5][6][7][8], were measured in several recent experiments on shock propagation in thin aluminum films [9][10][11][12][13][14]. For example, Winey et al [9] and Gupta et al [10] found elastic wave pressures up to 1 GPa, and Smith et al [11] reported a value around 2.7 GPa in relatively thin Al films up to 100 μm.…”

“…For example, Winey et al [9] and Gupta et al [10] found elastic wave pressures up to 1 GPa, and Smith et al [11] reported a value around 2.7 GPa in relatively thin Al films up to 100 μm. Very recently, elastic waves with amplitudes up to 12 GPa were discovered in laser-driven SW wave experiments using very thin Al films up to 10 μm, for which the time evolution of the elasticplastic SW profiles were measured with 10 ps time resolution [12][13][14].…”

Prospects for achieving high dynamic compression with low energy

“…Historically, shock wave experiments use compression times much longer than a nanosecond, which is a typical time resolution. Within the last two decades, methods to characterize shock waves with picosecond time resolution have been developed [7][8][9][10][11] , resulting in the measurement of enormous elastic compression on short time scales [12][13][14] , and the measurement of a tens of picosecond scale plastic shock rise time in aluminum 12 . These experiments require orders of magnitude less compression energy than longer time scale experiments to obtain and characterize comparable thermodynamic conditions, because the volume of compressed material is much smaller (i.e.…”

MD simulations of laser-induced ultrashort shock waves in nickel

“…Over the last several years, irradiation by ultrashort laser pulses has emerged as an efficient generator of shock waves with durations on the order of several tens to hundreds of picoseconds [1][2][3][4]. In particular, shock waves generated by femtosecond laser pulses, which have durations on the order of many atomic-scale processes, provide a unique opportunity to probe the response of materials to extreme conditions.…”