electromagnetic pulse

Short definition from Wiktionary

Noun

1. 1
   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.
2. 2
   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.