Charging of composites in the space environment

The space environment includes high-energy charged particles, which deposit in the composite materials of satellites. The deposited particles create a n electric field, which may grow until an electrostatic discharge occurs. A one-dimensional finite difference model has been developed, which calculat es the electric field in space and time as a function of the environment, m aterial properties, and boundary conditions. Using the electron and proton flux for a 7000-km-altitude orbit and the material data for a typical organ ic polymer, the calculated steady-state electric held is approximately 4400 V/m with a steady-state development time of 1.3 s. This is several orders of magnitude lower than the dielectric strength of the material, 15 MV/m. B ased on sensitivity studies done by varying particle fluxes and material pr operties several orders of magnitude around typical values, it was conclude d that typical Bur levels do not cause significant deep dielectric charging in typical composite materials. However, discharges can occur during subst orms when particle flux levels can rise by several orders of magnitude.