Impact of Spacecraft Shielding on Direct Ionization Soft Error Rates

Fig. 1: SiO2 sensitive volume (called SV1 in Table I) soft error rate relationships for several different space environments behind 2.5 mm of solid aluminum spherical shielding. All environments are derived from CREME96 with the exception of trapped protons and PSYCHIC. The deposited energy becomes the critical energy once a bin is chosen and the rate evaluated. The symbols are sparse to aid viewing – there are 240 bins per trace. The rate curve family for the silicon sensitive volume (called SV2 in Table I) is similar. Note that the PSYCHIC and trapped proton environments are cumulative fluences that were scaled by the inverse of the integration period to convert them to average rates. Abstract— We use ray tracing software to model various levels of spacecraft shielding complexity and energy deposition pulse height analysis to study how it affects the direct ionization soft error rate of microelectronic components in space. The analysis incorporates the galactic cosmic ray background, trapped proton, and solar heavy ion environments as well as the October 1989 and July 2000 solar particle events.