electromagnetic pulse

:  a pulse of high-intensity electromagnetic radiation generated especially by a nuclear blast high above the earth's surface and held to disrupt electronic and electrical systems Any nuclear bomb detonated high above the atmosphere bathes the area below in a powerful electromagnetic pulse (EMP) that is likely to burn out delicate electronic chips, transistors, computers and power and communication systems. The pulse happens at the speed of light, covering an entire continent. — William Broad —abbreviation EMP