Fusion starter. The Z machine at Sandia National Laboratories.

Electrical Pinch Fuses Hydrogen

PHILADELPHIA--The electric squeeze has come of age. For the first time, scientists have induced deuterium to fuse by using an electrical "pinch." Scientists now report that they have compressed a fuel pellet by a factor of 10, heated it up to over 2 million degrees kelvin, and created a microscopic hydrogen bomb in a bottle.

Fusion is the source of the sun's power. When light elements such as deuterium--a hydrogen with an extra neutron--collide with each other with sufficient force, they can stick together, creating a heavier element. This process releases a great deal of energy, so many scientists hope that fusion will eventually be a tremendous source of usable power. However, it takes a lot of heat and pressure to get the fusion reaction going. Scientists have done this with magnetic donuts, lasers, and atom bombs. Now the "Z machine" at Sandia National Laboratories in Albuquerque, New Mexico, is providing a new method.

The machine stores an enormous amount of electrical energy and then releases it all at once into a ring of 360 fine tungsten wires, each about a tenth of the diameter of a human hair. The intense current creates magnetic and electric fields that cause the wires to slam onto a chunk of plastic that has an embedded pellet of deuterium 2 millimeters across. The impact results in x-rays that, absorbed and reemitted by the imploding wires, compress the pellet and heat it to about 2.3 million degrees kelvin. Sandia physicist Ramon Leeper announced at the American Physical Society meeting here this week that the Z machine team then detected neutrons that were spit out when the deuterium inside the pellet fused, creating helium. "This is the first time that a pure electrical device has achieved these kind of densities and temperatures," he says, adding that it is also "the first observation of thermonuclear neutrons" from a device of this sort.

"This has been an extremely successful program, and they deserve a lot of credit," says Cornell University's David Hammer, and although the achievement is leagues away from leading to a practical energy source, he adds that the Sandia evidence for fusion is "the first step on a long road" toward an electrically driven fusion power plant. That'll do in a pinch.

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Posted in Physics