High Altitude Emp Detonations example essay topic

Electromagnetic Pulse has been known of since the 1940's when nuclear weapons were being trialed and produced. Yet, due to the lack of sufficient data the exact effects of EMP were not fully known until 1962. During this time a series of tests were being conducted which were code named 'Fishbowl'. "An electromagnetic pulse consists of a broadband, high intensity, short duration burst of electromagnetic energy. If nuclear detonation occurs, the electromagnetic pulse consists of a continuous frequency spectrum. Most of the energy is distributed throughout the lower frequencies of 3 Hz and 30 kHz".

(1) Electromagnetic pulse can also consist of the electromagnetic radiation from a nuclear explosion caused by Compton-recoil electrons and photoelectrons from photons scattered in the materials of the nuclear device or in a surrounding medium. The electric and magnetic fields generated by the blast may encounter with electrical or electronic systems to produce damaging current and voltage surges. It can also be caused by nonnuclear means. In today's society, electromagnetic pulse can have devastating effects with our increasing dependence on electronic devices to govern the way in which we live our lives. High altitude nuclear detonation of strategically positioned E-Bombs (EMP bombs) are possibly the most devastating weapons in today's arsenal.

Not deadly by means of instant massive fatalities, but deadly for its power to completely wipe out all unprotected electronic circuits. Through destroying controlling hardware which would wipe out the power grid, water, sewage and transportation. The famine that would result from the sudden loss of utilities would kill more people than any type of nuclear, biological or chemical weapon. To give an idea of the immense power of the weapon only three strategically placed detonations would wipe out the entire United State's electronic infrastructure. There are three main types of explosions when dealing with the effects of electromagnetic pulse. There are near-surface bursts up to 1.2 miles, medium-altitude bursts 1.2 miles to 19, and high-altitude bursts greater than 19 miles above the earth's surface.

"The greatest effect on surface bursts is caused by the ground. Unlike in the air, the gamma rays cannot escape the blast in all directions. For this reason, near-surface bursts are also in this category. Although they may not be on the ground, they have similar effects.

The ground absorbs many of the gamma rays. This produces an asymmetric field. The resulting field is very similar to that of a hemisphere that is radiating upward. The electrons also are able to return to the burst point through the ground. This makes the area near the centre of the burst contain a high concentration of highly ionized particles.

This net movement of electrons creates current loops that generate a magnetic field running around the burst point". (2) If the nuclear explosion occurs in the medium-altitude range, the effects of the ground are greater. Medium-altitude blasts range away from the ground but below the upper atmosphere. As the height of detonation increases, the asymmetry of the magnetic field produced lessons. "However, the asymmetry increases, after a point, with altitude due to changes in atmospheric density". (3) High altitude EMP detonations occur in an area of low density in the earth's upper atmosphere.

Due to the low density of the blast area, the gamma rays are able to travel much further before they are absorbed. The gamma rays then travel downward into the increasingly dense atmosphere, this is the point at which they interact with the air to ionize. "This region, called the deposition or source region, is roughly circular. It is thick in the middle and thinner toward the edges.

It extends horizontally very far creating source regions that are over 1000 miles in diameter". (4) The size of the source region depends on the height of detonation and the power of the weapon. The EMP in this source region gets deflected downward towards the earth due to the earth's magnetic field. High-altitude bursts are possibly the most dangerous type of EMP. Electromagnetic blasts contain huge amounts of electrical energy with the EMP from one hydrogen bomb detonated 300 km over the centre of Australia has the potential to set up an electrical field 50 kV / m strong over the whole of Australia. There are currently specific weapons that are designed to emit an electromagnetic pulse these weapons come under the term of an E-Bomb.

There are though methods in which electronic components are to some extent hardened against such weapons. The basic approach to hardening equipment is to provide a shield that prevents damaging electrical pulses entering a system. This requires protection of all electrical and mechanical penetrations. The cost of EMP hardening is quite high and is considered whether it is economically worthwhile to provide protection for the component before it is hardened against the effects of EMP. "To ignite an E-bomb, a starter current energies the stator coil, creating a magnetic field. The explosion (A) expands the tube, short-circuiting the coil and compressing the magnetic field forward (B).

The pulse is emitted (C) at high frequencies that defeat protective devices like Faraday Cages". (5) In conclusion the effects of EMP are real and will not be disappearing soon. The full extent of the effects of EMP is not yet fully known and is an imposing problem on the world as we are heading towards a more electronically dependent society. If war was to occur and use the full extent of the power of EMP then we could possibly be living in a world similar to the dark ages.

Bibliography

(1) web (2) Ibid. pp. 515-517. (3) International Union of Radio Science, "Nuclear Electromagnetic Pulse and Associated Effects", Telecommunication Journal, Vol 52, p. 57. (4) Ibid. p. 6. (5) To ignite an E-Bomb, John Batchelor.