In the blink of an eye, electromagnetic bombs could throw civilization back 200 years. And terrorists can build them for next to nothing.
The Next Pearl Harbor
The next Pearl Harbor will not announce itself with a searing flash of nuclear light or with the plaintive wails of those dying of Ebola or its genetically engineered twin. You will hear a sharp crack in the distance. By the time you mistakenly identify this sound as an innocent clap of thunder, the civilized world will have become unhinged. Fluorescent lights and television sets will glow eerily bright, despite being turned off. The aroma of ozone mixed with smoldering plastic will seep from outlet covers as electric wires arc and telephone lines melt. Your Palm Pilot and MP3 player will feel warm to the touch, their batteries overloaded. Your computer, and every bit of data on it, will be toast. And then you will notice that the world sounds different too. The background music of civilization, the whirl of internal-combustion engines, will have stopped. Save a few diesels, engines will never start again. You, however, will remain unharmed, as you find yourself thrust backward 200 years, to a time when electricity meant a lightning bolt fracturing the night sky. This is not a hypothetical, son-of-Y2K scenario. It is a realistic assessment of the damage the Pentagon believes could be inflicted by a new generation of weapons--E-bombs.
Illusttation by Edwin Herder
The first major test of an American electromagnetic bomb is scheduled for next year. Ultimately, the Army hopes to use E-bomb technology to explode artillery shells in midflight. The Navy wants to use the E-bomb's high-power microwave pulses to neutralize antiship missiles. And, the Air Force plans to equip its bombers, strike fighters, cruise missiles and unmanned aerial vehicles with E-bomb capabilities. When fielded, these will be among the most technologically sophisticated weapons the U.S. military establishment has ever built.
There is, however, another part to the E-bomb story, one that military planners are reluctant to discuss. While American versions of these weapons are based on advanced technologies, terrorists could use a less expensive, low-tech approach to create the same destructive power. "Any nation with even a 1940s technology base could make them," says Carlo Kopp, an Australian-based expert on high-tech warfare. "The threat of E-bomb proliferation is very real." POPULAR MECHANICS estimates a basic weapon could be built for $400.
An Old Idea Made New
The theory behind the E-bomb was proposed in 1925 by physicist Arthur H. Compton--not to build weapons, but to study atoms. Compton demonstrated that firing a stream of highly energetic photons into atoms that have a low atomic number causes them to eject a stream of electrons. Physics students know this phenomenon as the Compton Effect. It became a key tool in unlocking the secrets of the atom.
Ironically, this nuclear research led to an unexpected demonstration of the power of the Compton Effect, and spawned a new type of weapon. In 1958, nuclear weapons designers ignited hydrogen bombs high over the Pacific Ocean. The detonations created bursts of gamma rays that, upon striking the oxygen and nitrogen in the atmosphere, released a tsunami of electrons that spread for hundreds of miles. Street lights were blown out in Hawaii and radio navigation was disrupted for 18 hours, as far away as Australia. The United States set out to learn how to "harden" electronics against this electromagnetic pulse (EMP) and develop EMP weapons.
America has remained at the forefront of EMP weapons development. Although much of this work is classified, it's believed that current efforts are based on using high-temperature superconductors to create intense magnetic fields. What worries terrorism experts is an idea the United States studied but discarded--the Flux Compression Generator (FCG).
A Poor Man's E-Bomb
An FCG is an astoundingly simple weapon. It consists of an explosives-packed tube placed inside a slightly larger copper coil, as shown below. The instant before the chemical explosive is detonated, the coil is energized by a bank of capacitors, creating a magnetic field. The explosive charge detonates from the rear forward. As the tube flares outward it touches the edge of the coil, thereby creating a moving short circuit. "The propagating short has the effect of compressing the magnetic field while reducing the inductance of the stator [coil]," says Kopp. "The result is that FCGs will produce a ramping current pulse, which breaks before the final disintegration of the device. Published results suggest ramp times of tens of hundreds of microseconds and peak currents of tens of millions of amps." The pulse that emerges makes a lightning bolt seem like a flashbulb by comparison.
An Air Force spokesman, who describes this effect as similar to a lightning strike, points out that electronics systems can be protected by placing them in metal enclosures called Faraday Cages that divert any impinging electromagnetic energy directly to the ground. Foreign military analysts say this reassuring explanation is incomplete.
The India Connection
The Indian military has studied FCG devices in detail because it fears that Pakistan, with which it has ongoing conflicts, might use E-bombs against the city of Bangalore, a sort of Indian Silicon Valley. An Indian Institute for Defense Studies and Analysis study of E-bombs points to two problems that have been largely overlooked by the West. The first is that very-high-frequency pulses, in the microwave range, can worm their way around vents in Faraday Cages. The second concern is known as the "late-time EMP effect," and may be the most worrisome aspect of FCG devices. It occurs in the 15 minutes after detonation. During this period, the EMP that surged through electrical systems creates localized magnetic fields. When these magnetic fields collapse, they cause electric surges to travel through the power and telecommunication infrastructure. This string-of-firecrackers effect means that terrorists would not have to drop their homemade E-bombs directly on the targets they wish to destroy. Heavily guarded sites, such as telephone switching centers and electronic funds-transfer exchanges, could be attacked through their electric and telecommunication connections.
Knock out electric power, computers and telecommunication and you've destroyed the foundation of modern society. In the age of Third World-sponsored terrorism, the E-bomb is the great equalizer.
First published in Popular Mechanics September 2001
Illustration by John Batchalor
To ignite an E-bomb, a starter current energizes the stator coil, creating a magnetic field. The explosion expands the tube, sort-circuiting the coil and compressing the magnetic field forward. The pulse is emitted at high frequencies that defeat protective devices like Faraday Cages.
Last updated 04/11/2002