Weapons experts and techno-thriller fans are familiar with the concept of an electromagnetic pulse (EMP) — a supermassive blast of electricity, usually from a nuclear blast high above ground, that fries electronic circuits for miles around, crippling computers, cars and most other modern gadgets.

Now comes word that a much smaller EMP device, or "e-bomb," could be carried in a car, or even on someone's person — and be used to take down an airliner.

"Once it is known that aircraft are vulnerable to particular types of disruption, it isn't too much of a leap to build a device that can produce that sort of disruption," Israeli counter-terrorism expert Yael Shahar tells New Scientist magazine. "And much of this could be built from off-the-shelf components or dual-use technologies."

Shahar says she's especially worried about two devices — one called a Marx generator, which beams an EMP at a target, and the other with the "Back to the Future"-like name of flux-compression generator.

The latter was developed by the Soviets during the 1950s when Marx generators proved too expensive. Basically, an explosive charge is set off at one end of a cylinder of charged copper coils, and the resulting shock wave sends out a powerful electric pulse as it travels down the tube.

It might take a big flux-compression generator to darken a city neighborhood. But a smaller one could take out the steering, navigation and communication systems of a jetliner, especially if pointed at the cockpit.

As for Marx generators, which are used by power companies, medical researchers and labs, you can buy the plans to build one online for $10, or a fully assembled commercial unit for several hundred dollars.

Shahar adds that as aircraft manufacturers switch to lighter, stronger composite materials in place of aluminum, they're actually making the planes more vulnerable.

"What is needed is extensive shielding of electronic components and the vast amount of cables running down the length of the aircraft," she tells New Scientist.

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