In the 1980s, people feared neutron bombs that could kill everyone but leave buildings, roads, and cars intact. Today, we should fear a different kind of nuclear threat that can instantaneously destroy power grids, electronic systems, and communications along an entire coast but spare people.
The Electro Magnetic Pulse (EMP) effect was first observed during the early testing of high altitude airburst nuclear weapons. The effect is characterized by the production of a very short (hundreds of nanoseconds) but intense electromagnetic pulse, which propagates away from its source with ever diminishing intensity, governed by the theory of electromagnetism. The Electro Magnetic Pulse is in effect an electromagnetic shock wave. This pulse of energy produces a powerful electromagnetic field, particularly within the vicinity of the weapon burst. The field can be sufficiently strong to produce short lived transient voltages of thousands of Volts (ie, kilo Volts) on exposed electrical conductors, such as wires, or conductive tracks on printed circuit boards, where exposed.
The conceivable targets for an HPEM attack could be telecom, radio/TV networks, power system network, air traffic control, rail networks, banking and government administrative networks etc.. The technology base which may be applied to the design of electromagnetic bombs is both diverse, and in many areas quite mature. Key technologies which are extant in the area are explosively pumped Flux Compression Generators (FCG), explosive or propellant driven Magneto-Hydrodynamic (MHD) generators and a range of HPM devices, the foremost of which is the Virtual Cathode Oscillator or Vircator. A wide range of experimental designs have been tested in these technology areas, and a considerable volume of work has been published in unclassified literature.