Effect of Various Tamper Materials on Ablation and Shock Generation in Aluminum and Titanium Ablators

Objects in exo-atmosphere are vulnerable to degradation and failure from high-energy electromagnetic radiation. A high-power, nanosecond pulse laser is used to investigate these effects on our ablator materials of interest, aluminum and titanium. We vary ablator thickness to 25 um, 50 um, and 100 um. Samples incorporate three different types of tamper materials, sapphire, lithium fluoride, and fused silica. A tamper is an optically transparent medium placed on the incident side of the ablator which produces a higher rear-surface velocity and front-surface pressure through energy confinement. Experiments were carried out using three intensities: 10⁹, 10¹⁰, and 10¹¹ Wcm^-2 with a constant pulse length of 10 ns. Thus, this study investigates the effect of varying ablator thickness across two ablator materials, three tamper materials, and three intensities on ablation dynamics. Diagnostics include dual-frame interferometry to obtain time-resolved electron density and velocity profiles and XUV emission spectroscopy to determine plasma temperature, composition, and ionization states. We will show how tampers alter laser-matter interactions and plasma plume behavior.

*Work supported by the Defense Threat Reduction Agency under Award No. HDTRA12020001.