Investigating the velocity envelope of laser-driven micro-flyers for hypervelocity impact experiments

Abstract

Protection materials are continuously facing higher velocity threats; characterizing their response to these threats is necessary to improve performance. We have previously examined failure of boron carbide and magnesium systems at strain rates of up to 105 per second [12,13]. To study dynamic deformation at higher strain rates closer to the hypervelocity regime, we use micro-flyers to impact target materials. Over the last two decades, pulsed lasers have proven to be effective drivers for micro-flyers when achieving hypervelocity impacts. However, control of the experiment requires good characterization of the flyer behavior [11] and velocities. Here, we explore the velocity regime for a tabletop laser-driven flyer system as a function of laser pulse conditioning (fluence, pulse duration, etc.),and launch package materials. We modify an established model to inform the selection of launch package substrates and configuration in a lens-coupled micro-flyer apparatus. We use Photon Doppler Velocimetry (PDV) to obtain velocity histories of the flyers [10]. Comparisons between flyer data from our launcher system and the model predictions uncover the important parameters controlling launcher performance.