A Spark of Hope for Fusion

A new device clears an obstacle to a type of fusion power plant.

By Kevin Bullis

Fusion future? Sandia researcher Bill Fowler tests circuits on a device designed to produce large electrical impulses rapidly and repeatedly. Groups of such devices could be used to initiate nuclear fusion. Each element of the system features a pair of large capacitors and a switch arranged in a configuration that minimizes current-slowing magnetic fields.

A new device could bring high-yield nuclear fusion for generating electricity a step closer to reality, according to researchers at Sandia National Laboratories, in Albuquerque, NM. The technology, developed by Sandia researchers in collaboration with the Institute of High Current Electronics, in Tomsk, Russia, can deliver very brief bursts of extremely large amounts of electricity and do it every 10 seconds thousands of times in a row. The researchers still need to use the device to produce a continuous series of miniature nuclear explosions that could heat water and drive turbines in a fusion power plant.

The Sandia device stores energy in a group of large capacitors and releases it very quickly, in just 100 nanoseconds. A new kind of physical arrangement of these capacitors prevents magnetic fields from forming and slowing electrical current, a major problem with previous devices. But while acknowledging that the technology is an important advance for delivering pulses of power, several experts say a power plant based on such technology faces significant hurdles, not the least of which is building the plant sturdy enough to withstand the strong explosions going off every 10 seconds.

While scientists have long known how to produce fusion--it's the heart of the hydrogen bomb--they've yet to find a way to harness that power in a power plant. Currently, the favored path to high-yield fusion that produces more energy than it consumes involves creating an ultrahot plasma and containing it within a magnetic field. An experimental machine designed to demonstrate such a concept is being built by a large international consortium in the south of France, and it's scheduled to be completed in about 10 years. (See "International Fusion Research.") But even if the project is successful, commercial-scale fusion power plants will still be decades away, as researchers will need to find ways to economically harvest the energy released by the fusion reactions.

Meanwhile, researchers have been routinely creating small amounts of fusion in the lab using a different technique, called inertial confinement. Here fusion starts when a small pellet of fuel is compressed by a burst of energy, which can be from different sources, including lasers. At Sandia, inertial confinement is now done with the Z machine, which uses electricity to create a burst of x-rays that compress the pellet. While such machines are good for helping to simulate nuclear weapons, they produce only a modest amount of fusion, releasing only a small part of the energy in the fuel.