A Flux Compression Generator is basically a Directed Electro-Magnetic Pulse (DEMP) gun. There are a number of uses for this technology, most of them related to warfare.

The EMP effect

The Electro-Magnetic Pulse (EMP) effect was first observed during the early testing of high-altitude airburst nuclear weapons. The effect is characterised by the production of a very short but intense EMP, which propagates away from its source with diminishing intensity. The EMP is in effect an electro-magnetic shock wave.

Computer equipment is very vulnerable to EMP effects, since computers contain high density Metal Oxide Semiconductor devices, which are very sensitive to high voltages. Very little energy is required to permanently destroy them. A voltage in excess of ten volts can effectively destroy the device. Even if the pulse was not powerful enough to cause immediate damage, the power supply to the equipment would readily supply enough additional energy to complete the job. With the constant miniaturisation of semiconductor devices the danger from EMP increases.

Shielding the electronics provides only limited protection, since any cable connected to the equipment will behave very much like an antenna, in effect guiding the high voltage into the equipment.

The Flux Compression Generator

One of the offshoots of this research is the Flux Compression Generator, essentially a very simple weapon. It consists of a metal tube packed with explosives and wrapped with a copper coil. The coil is energised by a bank of capacitors and promptly detonated at the peak of the magnetic field. Once detonation occurs, the metal tube flares outwards. This causes the coil to short-circuit along its length. This propagating short-circuit has the effect of compressing the magnetic field while reducing the inductance of the coil.

This produces a rapidly-increasing current pulse, which breaks before the final disintegration of the device.

The effects of EMP can be prevented or reduced by using a Faraday Cage. This method does, however, currently have a few known weaknesses. The first is that very-high-frequency pulses, in the microwave range, can worm their way around vents in Faraday Cages. The second concern is known as the 'Late-time EMP Effect', which occurs around 15 minutes after the detonation. The EMP, surging through electrical systems, creates localised magnetic fields. When these magnetic fields break down, they can cause electric surges to travel back through the power and telecommunications systems.