Electromagnetic pulse

An electromagnetic pulse (EMP) is a burst of electromagnetic radiation that results from a nuclear explosion that disables many forms of electronic devices. After nuclear detonation, the EMP starts with a short, intense burst of gamma rays which interact with the atoms in air molecules, and electrons are released through a process called the Compton Effect. The electrons ionize the atmosphere and generate a powerful electrical field. The strength and effect of the EMP depends highly on the altitude at which the bomb detonates and the local strength of the Earth’s magnetic field.

It is estimated today that if a single nuclear bomb was exploded 250 miles above Kansas, the entire continental U.S would be affected, due to the greater strength of the Earth’s magnetic field over the U.S. Even the water supply would be affected, given that it relies on electrical pumps.

Less-powerful EMPs can be produced through explosively pumped fluxed compression generators, which are essentially normal electrical generators driven by an explosion using conventional fuel. Electronic equipment can be protected from an EMP by placing it within a Faraday Cage, which is a metallic shield that can divert the electromagnetic energy directly to the ground.