Physics of EMP
A "natural" EMP can be created by a storm on the surface of the sun that ejects a mass of particles that hit the Earth. A moderately strong natural EMP occurred in 1989 and created damage to the electric grid in Canada and the Northeastern USA. A natural EMP caused by the sun will mainly affect the electrical grid.
A man-made EMP can be generated by exploding a nuclear weapon in near space above the atmosphere.
Unfortunately either type of EMP, natural or man-made, has the potential to put the grid down for years because high voltage transformers are inadequately protected and it would take years to replace or repair them. These transformers are often as large as a house and are custom manufactured with typical lead times of a year or more. Most of the suppliers are located outside of the U.S.
When a nuclear weapon explodes it releases energy in several different ways. About 1% of the energy is released as gamma rays. Gamma rays are like x-rays but far more energetic. When a bomb is exploded hundreds of miles above the Earth, the gamma rays are emitted in all directions. The gamma rays that are directed downward pass through space unimpeded until they reach the highest and thinnest regions of the atmosphere, about 40 miles above the surface of the Earth. In the thin, extreme upper atmosphere, the gamma rays start to encounter atoms of air. The air atoms have a heavy nucleus surrounded by a cloud of light electrons. Gamma rays can interact with the electrons and violently knock electrons out of the atoms and send the electrons flying toward the Earth at a very high velocity, a velocity approaching the speed of light or 186,000 miles per second. The interaction of gamma rays with electrons is called the Compton Effect. Electrons have a negative electric charge. A charged particle moving through a magnetic field is deflected by the magnetic field. The rapidly moving electrons are deflected by the Earth's magnetic field into a spiral path. Electrons deflected by a magnetic field strongly radiate electromagnetic waves.
A man-made EMP can be generated by exploding a nuclear weapon in near space above the atmosphere.
Unfortunately either type of EMP, natural or man-made, has the potential to put the grid down for years because high voltage transformers are inadequately protected and it would take years to replace or repair them. These transformers are often as large as a house and are custom manufactured with typical lead times of a year or more. Most of the suppliers are located outside of the U.S.
When a nuclear weapon explodes it releases energy in several different ways. About 1% of the energy is released as gamma rays. Gamma rays are like x-rays but far more energetic. When a bomb is exploded hundreds of miles above the Earth, the gamma rays are emitted in all directions. The gamma rays that are directed downward pass through space unimpeded until they reach the highest and thinnest regions of the atmosphere, about 40 miles above the surface of the Earth. In the thin, extreme upper atmosphere, the gamma rays start to encounter atoms of air. The air atoms have a heavy nucleus surrounded by a cloud of light electrons. Gamma rays can interact with the electrons and violently knock electrons out of the atoms and send the electrons flying toward the Earth at a very high velocity, a velocity approaching the speed of light or 186,000 miles per second. The interaction of gamma rays with electrons is called the Compton Effect. Electrons have a negative electric charge. A charged particle moving through a magnetic field is deflected by the magnetic field. The rapidly moving electrons are deflected by the Earth's magnetic field into a spiral path. Electrons deflected by a magnetic field strongly radiate electromagnetic waves.