Emission Spectroscopy of Hypervelocity Impacts on Aluminum, Organic and High-Explosive Targets

Abstract

Laboratory experiments of hypervelocity impacts on aluminum, nylon and high-explosive targets are presented. Spectral measurements of the impact flash are recorded, together with radiometric measurements to derive the temperature of the flash. Such experiments aim at demonstrating that the impact flash produced by a ballistic missile interception contains the spectral information required to identify the content of the intercepted missile. It is shown that the elements that are part of the aluminum projectile and/or aluminum target are successfully identified from the obtained spectra. For the case of a nylon/aluminum target organic molecular emission lines characteristic of CN and C 2 are also identified. The CN molecular band is also observed for the case of a high-explosive target, although the detection of organic elements from such targets is more difficult than for nylon targets. In most cases, the temperature of the impact flash measured using the radiometer is in the range 2500 -4000 K, whereas a comparison between simulated and experimental spectra shows temperatures up to 9000 K. Hence a conclusive impact flash temperature could not be obtained.

Impact flash evolution of CO2 ice, water ice, and frozen Martian and lunar regolith simulant targets

“…Additionally, the photodiode centered at 400 nm would capture the strong Al atomic emission lines at 394.4 and 396.2 nm. These Al/AlO emission lines/bands have been observed in previous impact experiments (Schultz 1996;Schultz et al 1996;Heunoske et al 2013;Tandy et al 2014;Verreault et al 2015) and all other Al atomic and AlO molecular emission would fall outside of the spectral regions covered by the remaining photodiodes. Yafei et al (2019) also observed an earlier peak in the decay profile for the band-pass filtered photodiode centered at 400 nm, which would capture the aforementioned Al atomic emission.…”

“…2014; Verreault et al. 2015) and all other Al atomic and AlO molecular emission would fall outside of the spectral regions covered by the remaining photodiodes. Yafei et al.…”

“…These phases primarily comprise a rapid jet or plasma phase; a slower, expanding vapor cloud; and molten or high temperature ejecta that are dependent on specific impact parameters (Ang 1990;Yang et al 1992; Kadono and Fujiwara 1996;Schultz 1996;Sugita et al 1998;Sugita and Schultz 1999;Schultz 2004, 2007;Schultz et al 2006;Tsembelis et al 2008;Ernst et al 2011;Bruck Syal et al 2012). Several studies have also utilized spectroscopic instrumentation to further analyze the composition of the rapidly evolving ejecta plume, allowing determination of prevalent atomic and/or molecular species (Gehring and Warnica 1963;Jean and Rollins 1970;Schultz et al 1996Schultz et al , 2007Sugita et al 1998Sugita et al , 2003Schultz 1999, 2003a;Lawrence et al 2006;Tandy et al 2014;Schultz and Eberhardy 2015;Verreault et al 2015).…”