These changes come in many forms, including single event latchup, single event burnout and single event upset. Single event gate rupture and single event dielectric rupture can occur as well.
Single event latchup is when you have a parasitic transistor in a device that is not intentionally there and a particle passing through a sensitive spot in the device turns the transistor on. When this occurs, there is no way to turn the transistor off. As a result, if power isn’t removed quickly, thermal runaway, and energy and heat levels that the material of the device cannot withstand, can occur, melting device components.
Single event upset produces errors in circuits as charged particles ionize the medium that they pass through. In the process, they leave behind a wake of electron-hole pairs. SEUs are non-destructive, transient soft errors. Devices that are reset or rewired can resume normal functioning. SEUs are often single bit upsets, which are bit flips in memory cells or registers. Adjacent bit or multi bit upset can occur, as well, if a single particle hits two or more bits and produces simultaneous errors.
There are a number of other non-destructive SEEs. For example, single event transients (SETs) are an analog response that manifests as a turn-on or turn-off of voltage in which voltage peaks and then resettles. This can be a problem if downstream electronics can’t handle the change.
Stuck bits (or persistent single event upsets) are another possible problem, as are single event functional interrupts (SEFI) in which hits to the control circuitry for accessing memory or a device require power cycling or other actions to correct the problem.
Given their potential for producing anything from minor, transient issues to catastrophic failures, it is important that all components and devices designed for use in aerospace devices be thoroughly tested. Procedures like SET tests, SEL tests and SEE tests in general can help designers and manufacturers isolate, identify and address adverse single event effects.