EMP Long Beach[/caption]
HEMP
HEMP generation. HEMP is caused by a nuclear burst at high altitudes. Prompt gamma rays following the nuclear detonation are the principal source of HEMP. This gamma radiation causes bursts of electron flow from the Compton effect, a photoelectric effect, and a “pair production” effect. Of these three effects, however, the primary source of HEMP is the Compton effect.
Gamma radiation. At high altitudes (above 30 kilometers), the atmosphere is thin and thus allows gamma radiation from the nuclear burst to travel out radially for long distances. Below the center of the burst, however, the atmospheric density increases as the earth’s surface is approached. The prompt gamma rays propagate toward the earth in a thin spherical shell, moving at the speed of light away from the burst…
Compton scattering. When the downward directed rays encounter the upper regions of the atmosphere, they begin to interact with the atoms (or molecules) of the atmosphere at a rate which is a function of atmospheric density and burst conditions. The dominant interaction is Compton scattering, in which the energy of a gamma ray is partially transferred to an electron of an air atom (or molecule). The electron then begins traveling in approximately the same direction as the gamma ray. The other product of collision is a gamma ray of reduced energy. The spherical shell of gamma rays is converted during Compton scattering into a spherical shell of accelerated electrons.
