Tom Harris explains the nuclear EMP threat — and how researchers discovered it largely by accident:
In 1958, American tests of hydrogen bombs yielded some surprising results. A test blast over the Pacific Ocean ended up blowing out streetlights in parts of Hawaii, hundreds of miles away. The blast even disrupted radio equipment as far away as Australia.Researchers concluded that the electrical disturbance was due to the Compton effect, theorized by physicist Arthur Compton in 1925. Compton’s assertion was that photons of electromagnetic energy could knock loose electrons from atoms with low atomic numbers. In the 1958 test, researchers concluded, the photons from the blast’s intense gamma radiation knocked a large number of electrons free from oxygen and nitrogen atoms in the atmosphere. This flood of electrons interacted with the Earth’s magnetic field to create a fluctuating electric current, which induced a powerful magnetic field. The resulting electromagnetic pulse induced intense electrical currents in conductive materials over a wide area.
You don’t need to detonate a nuclear weapon in the atmosphere though. You can instead detonate a non-nuclear flux compression generator bomb — which, really, sounds like something straight out of a bad sci-fi show:
The bomb consists of a metal cylinder (called the armature), which is surrounded by a coil of wire (the stator winding). The armature cylinder is filled with high explosive, and a sturdy jacket surrounds the entire device. The stator winding and the armature cylinder are separated by empty space. The bomb also has a power source, such as a bank of capacitors, which can be connected to the stator.
- A switch connects the capacitors to the stator, sending an electrical current through the wires. This generates an intense magnetic field.
- A fuze mechanism ignites the explosive material. The explosion travels as a wave through the middle of the armature cylinder.
- As the explosion makes its way through the cylinder, the cylinder comes in contact with the stator winding. This creates a short circuit, cutting the stator off from its power supply.
- The moving short circuit compresses the magnetic field, generating an intense electromagnetic burst.
