ELECTROMAGNETIC PULSE PROTECTION (EMPP)
The Nuclear Electromagnetic Pulse is a product of a nuclear explosion. The phenomena has been known since the late 1950s. The characteristics of the electromagnetic radiation resulting from the nuclear explosion depend on the altitude at which the explosion occurs. The three categories are; high altitude, air burst and surface burst NEMP. The source of electromagnetic radiation is basically the same in all cases. The high energy Gamma Radiation from the nuclear explosion collides with the air molecules in the earth’s atmosphere and dislodges electrons from these molecules which then become free to move rapidly away from their parent molecule. These free electrons are known as Compton Electrons and the movement of the charge is known as Compton Current.
The difference between the three categories of NEMP is the way in which the Compton Electrons and the resulting Compton Current produce the electromagnetic field.
In an inhomogeneous medium (such as the ground burst case) the recombination rate of mobile active particles is asymmetrical. This produces a net flow of current rather like a dipole. In the case of high altitude EMP the electrons released in the upper atmosphere by the incident Gamma rays encounter the earth’s magnetic field. This causes them to spiral round the field, thus producing a huge line of current loops. This is the dominant source of electromagnetic radiation in the high altitude EMP. The field produced is of high magnitude (over 50kV/m ) and has a very fast rise time (nS). Because of the high altitude the area of coverage is enormous. It is worth noting that NEMP is the only significant effect of an exo-atmospheric nuclear explosion. Therefore it can be of extreme strategic importance. For this reason electrical and electronic systems which are required to continue to function throughout a serious conflict MUST be unaffected by NEMP.
The frequency spectrum for a nuclear electromagnetic pulse contains frequency components from 1kHz right up to approximately 10GHz. The protection of electronic equipment from such a large and varied field presents special problems.
EEP can design, supply, install and test all aspects of EMPP facilities from the integration of the EMPP shield panels to the protection of all penetrations into the EMPP shield from electrical cables to water pipes.
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