Noun
A short-duration burst of high-intensity electromagnetic radiation generated by a physical event, in particular by a large thermonuclear explosion in the atmosphere. The pulse causes a damaging surge of voltage within electrical and electronic systems.
Compton-recoil electrons and photoelectrons from photons scattered in the materials of a nuclear event causing electric and magnetic fields to couple with electrical and electronic systems to produce damaging current surges.
Source: en.wiktionary.org