Abstract :
Energy fluxes of particles at flight altitudes are calculated using the QARM or EXPACS codes. These fluxes for charged particles are extrapolated, by the inverse LET law, to low energies where the particles have their highest capability to induce SEU. The fluxes in air are used to calculate energy and LET fluxes in silicon. Secondary ion fluxes are calculated by our analytical model. All calculations have no adjustable parameters! The LET fluxes allow easy calculation of SEU rates in avionics by using the SEU cross section versus LET of the devices. We use the MULASSIS code to verify our approach. The model is particularly good for small feature size devices like modern SRAMs. The important ionizing particles (with increasing critical LET of the device), are protons, deuterons, alpha particles, and heavier ions. Muons, pions, tritons, 3He ions, and electrons have minor contributions. Examples of calculations of SEU rates in the atmosphere are provided.
Keywords :
avionics; deuterons; muons; pions; tritons; EXPACS code; MULASSIS code; QARM code; SEU rate; alpha particle; avionic; deuteron; energy flux; flight altitudes; heavier ion; high altitude; inverse LET law; particles ionization; sea level; secondary ion flux; Aerospace electronics; Alpha particles; Analytical models; Ions; Mesons; Analytical model for SEU rate; SEU rate in avionics; particle LET flux in silicon; terrestrial particle fluxes at low energies; total LET flux;
