Cosmic radiation effects on avionics

The earth is bombarded by a nearly isotropic flux of energetic charged particles called cosmic rays which interact with air nuclei to generate a cascade of secondary particles building up to a maximum intensity at 60 000 feet. At normal cruising altitudes, the radiation is still several hundred times the ground level intensity. These particles are sufficiently energetic and ionising that they can deposit enough charge in a smalt volume of semiconductor to change the state of a memory cell, while certain devices can be triggered into a state of high current drain, leading to burn-out and hardware failure. These deleterious interactions of individual particles are referred to as single event effects. The authors have flown Cosmic Radiation Effects detectors in a variety of spacecraft and aircraft and illustrative results will be presented together with a review of published instances of such phenomena in flight systems. In the future there is likely to be increased susceptibility due to growing reliance on high performance computers using smaller devices operated at lower voltages and flying at higher altitudes. The influence of cosmic rays will have to be properly considered in the assessment of reliability. (C) 1999 Published by Elsevier Science B.V.