Detection of electromagnetic pulses produced by hypervelocity micro particle impact plasmas

Hypervelocity micro particles (mass <1 ng), including meteoroids and space debris, routinely impact spacecraft and produce plasmas that are initially dense (similar to 10(28) m(-3)), but rapidly expand into the surrounding vacuum. We report the detection of radio frequency (RF) emission associated with electromagnetic pulses (EMPs) from hypervelocity impacts of micro particles in ground-based experiments using micro particles that are 15 orders of magnitude less massive than previously observed. The EMP production is a stochastic process that is influenced by plasma turbulence such that the EMP detection rate that is strongly dependent on impact speed and on the electrical charge conditions at the impact surface. In particular, impacts of the fastest micro particles occurring under spacecraft charging conditions representative of high geomagnetic activity are the most likely to produce RF emission. This new phenomenon may provide a source for unexplained RF measurements on spacecraft charged to high potentials. (C) 2013 AIP Publishing LLC.