Simple deceleration mechanism confirmed in the terminal hypervelocity impacted tracks in SiO2 aerogel

Abstract

As an attractive collector medium for hypervelocity particles, SiO2 aerogel has been deployed on outer space missions. Aiming at quantifying the complicated relationship between the penetration track and the residual grains, many attempts have been made on hypervelocity experiments and models. However, models were difficult to accord strictly well with experimental data attributed to many uncertainties including thermal effects, aerogel accretions and projectile ablation during the penetration. In this paper, impact experiments were conducted at various density silica aerogels (50∼120 kg·m−3) with regular soda-lime glass beads as projectiles. Varying degrees of thermal effects happened around and along track was observed by scanning electron microscopy. That energy distribution in the track released by hypervelocity projectile has a decreasing change. The regular data of the terminal A-β type track (the track with combined features) was found according to A-type tracks classification based on the conditions of vapor model (Domínguez, 2009). Just considering for projectile overcoming the crushing strength with uniform deceleration, the simple mechanism was confirmed by the data fitted well with the snowplow model (Domínguez et al., 2004). The result after tracks classification is due to the terminal track with few thermal effects and aerogel accretions. In addition, other two types of tracks formation processes were discussed.