The days of fusion-powered helicopters, tanks and trucks that can operate for months on end without refueling -- like today's nuclear-powered submarines and aircraft carriers -- may still be a long way off.
But scientists at California's Lawrence Livermore National Laboratory, which houses the National Ignition Facility, say they recently made a breakthrough by generating a fusion reaction that created more energy than it took in.
Fusion, which occurs naturally on the sun and makes energy by fusing atoms, is basically the opposite of fission, which creates energy by splitting them. The latter is the foundation for modern nuclear technology and, for decades, has been used on everything from military weapons and ships to commercial power plants.
Fusion has long been an attractive energy source to physicists because such a reactor could theoretically run on the same kind of hydrogen found in ocean water, produce little waste and avoid a catastrophic meltdown because the process doesn't lend itself to out-of-control chain reactions.
The California team, whose results were published online this week in the journal Nature, didn't produce a true fusion "ignition," according to an article by Joel Achenbach of The Washington Post. Overall, the experiment still required far more energy than it produced.
Scientists concentrated 192 lasers on a pellet of hydrogen fuel to compress it and trigger a fusion of the isotopes deuterium and tritium, according to the report. Only about 1 percent of the energy from the lasers entered the pellet, but the technique, known as "alpha heating," created a series of nuclear reactions that generated a higher level of particles and heat, it stated.
To have practical implications, the scientists would have to produce 100 times more fusion reactions, Mark Herrmann, director of the Pulse Power Sciences Center at the Sandia National Laboratories, a sister institution, told the newspaper.
Even so, the experiment is likely to excite military technologists, who have long dreamed of fusion-powered equipment that could roam a battlefield almost indefinitely and require minimal logistics networks.
The Marine Corps, for instance, has experimented in recent years with using solar panels rather than generators to charge radios and computers in Afghanistan, in part to limit the number of fuel convoys vulnerable to attack by insurgents.