Evidence for Multicomponent Arc Plasmas in Arecibo Arcing Data for 5 Satellites

Satellite solar array arcs in a vacuum produce visible light and radio frequency (RF) noise. Because the arc-sites are invariably triple points, where exposed conductors and insulators come together, the arc plasmas always contain at least a conductor (or semiconductor) and a dielectric. This was confirmed in 2008 by optical spectra of vacuum arcs in the laboratory. The arc plasma components expand away from the arc-site with speeds related by the inverse square roots of their masses. When the solar cells are laid down on a Kapton substrate, an ionized Kapton fragment may also be an arc plasma component. It has been shown in laboratory flashover studies with an aluminum/Kapton arc-site that a three-component arc plasma can be seen in the arc-current. In this paper, it is assumed that the RF EMI produced is proportional to the amplitude of the arc-current profile. Arecibo Observatory observations of satellite arc RF emissions are analyzed for 5 different MEO satellites. Gaussians fitted to the observed RF total power light curves for individual arcs show that the arc plasmas have multiple components, much like individual vacuum arcs in laboratory flashover tests. Because the peak times of the component Gaussians differ from one satellite type to another, satellite arc radio light curves may be used to characterize different satellite types. This may be helpful in space domain awareness observations.