Composition of Plasmas Formed from Debris Impacts on Spacecraft Surfaces

The threat of electrical anomalies caused by plasma resulting from hypervelocity impacts of meteoroids and space debris has thus far not been well characterised. Here we present results from a ground-based hypervelocity impact experiment with measurements of the impact plasma formed by iron projectiles impacting on representative spacecraft materials at speeds characteristic of both meteoroids and space debris. These experiments were conducted using a Van de Graaff dust accelerator with projectiles ranging from 10-16 to 10-11 g in mass. We find that a mixture of negative ion species are produced and ejected from negatively-biased impact surfaces, and that the dependence of electron production on impact speed is weaker for surfaces with a conductive coating.