First Contact: Fine Structure of the Impact Flash and Ejecta during Hypervelocity Impact

Abstract

Hypervelocity impacts are a major threat in low-earth orbit and in hypersonic applications. The mechanisms activated under these extreme conditions are typically obscured by a very bright flash, called the impact flash, that contains within it the signatures of the critical mechanisms, the impacting materials, and the impact environment. However, these signatures have been very difficult to observe because of the small length and time scales involved coupled with the high intensities associated with the flash. Here we perform experiments investigating the structure and characteristics of the impact flash using unprecedented temporally co-registered high-resolution diagnostics. Reciprocal impact configurations, in which the projectile and target material are swapped, are used to demonstrate the coupling of early-stage mechanisms in the flash and later-stage ejection mechanisms responsible for the development of the impact crater.