The Christofilos Effect refers to the entrapment of charged particles along magnetic lines of force that was first predicted in 1957 by Nicholas Christofilos. Christofilos suggested the effect had defensive potential in a nuclear war, with so many beta particles (electrons) becoming trapped that warheads flying through the region would see electrical currents so great that their trigger electronics would be damaged. The concept that a few friendly warheads could disrupt an enemy attack was so promising that a series of new nuclear tests was rushed into the schedule before a testing moratorium came into effect in late 1958. These tests demonstrated that the effect was not nearly as strong as predicted, and not enough to damage a warhead. However, the effect is strong enough to be used to black out radars and disable satellites.
Among the many different types of energy released by a nuclear explosion are a large number of beta particles, or high energy electrons, created by the nuclear fission reactions used in a typical nuclear bomb design. Because these particles are charged, they induce electrical currents into atoms as they pass them by at high speed, causing the atom to ionize while causing the beta to slow slightly. In the lower atmosphere this reaction is so powerful that the betas slow to thermal speeds within a few tens of meters at the most, but at high altitude they are free to travel long distances.
If a bomb is exploded above the atmosphere, those betas travelling downward will continue to do so until the atmosphere reaches a critical density, typically between 50 and 60 km. This causes a large disk of ionized air to form under the explosion point, causing nuclear blackout. A similar number, travelling upwards, will be lost to space. The Christofilos effect concerns those betas travelling roughly parallel to the Earth's magnetic field at the point of explosion. These betas, being charged, become trapped within the field and begin to travel north and south along the lines of force. Since these are curved and meet the ground near the north and south magnetic poles, these particles eventually hit the atmosphere as well, causing similar ionization disks to form.
The basic idea of the Christofilos effect is that the ionization disk can be created long distances from the explosion. For every possible detonation point in the southern hemisphere, for instance, there is a point in the northern hemisphere that is its magnetic conjugate area where the disk will form. Christofilos suggested the possibility that the betas could be used defensively. While flying through the beta cloud a reentry vehicle encounters the same sort of ionization effect as the air, but being metal, the resulting electron movement becomes an electrical current within the structure. If this effect is strong enough, the resulting currents within the warhead might damage it, especially its electronics. This could, in theory, be used as a defensive measure by setting off a series of bombs over the south Pacific, creating a blanket over most of the United States while not having to deal with any nuclear fallout or electromagnetic pulse from the bombs.
Just as interesting to military planners was the possibility of using this as an offensive weapon. In the case of an attack by US forces on the Soviet Union, the southern conjugate locations are generally in the Indian Ocean, where they would not be seen by Soviet early warning radars. A series of such explosions at low altitude over the Indian Ocean would cause a massive radar blackout over Russia, degrading their ABM system, without any warning. As these effects last as long as five minutes, about the amount of time that a line-of-sight radar in Russia would have of the warheads, careful timing of the attack could render the ABM system useless.
In 1957, Christofilos suggested that entrapment in the Earth's magnetic could be used deliberately to shape the spread of a nuclear weapon's betas. At first the concept was ignored. However, the launch of the Explorer I satellite in 1958 led to interesting anomalous readings that were determined to be due to what are now known as the Van Allen radiation belts, charged particles from the Sun that become trapped within the Earth's magnetic field. This led to panic within the defense establishment when some concluded that the Van Allen belts were not due to the Sun's particles, but secret Soviet high-altitude nuclear tests. Several follow-up launches were made to better characterize these belts, and the panic faded.
Christofilos, formerly engaged in civilian research only, was now invited to join the nuclear bomb team at the Lawrence Radiation Laboratory, although he never received the "Q clearance" needed to work on warhead designs. He proposed nuclear detonations to test his prediction. This was achieved in 1958 in Project Argus, when three atomic bombs were detonated over the south Atlantic at a height of 300 miles (480 km). The bombs released charged particles which behaved exactly as Christofilos had predicted, being trapped along the lines of force. Those that managed to get far enough within the atmosphere to the north and south set up a small magnetic storm.
These tests demonstrated that the possibility of using the effect as a defensive system simply did not work. The effect was neither strong enough nor long-lasting enough to be used as a defensive shield. The offensive possibilities remained, but with a lifetime on the order of a few minutes the effect would not last long enough to hide the entire attack, so a complete surprise attack would not be possible. This being the case, an even more powerful blackout could be created by warheads within the attack itself.
More recently, there has been continual concern about the use of the Christofilos effect as a way to disable satellites.
- Neufeld, Michael (2008). Von Braun: Dreamer of Space, Engineer of War. Vintage Books. ISBN 9780307389374.
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