LOS ANGELES — A tabletop experiment created nuclear fusion — long seen as a possible clean-energy solution — under lab conditions, scientists reported.

However, the amount of energy produced was too little to be seen as a breakthrough in solving the world's energy needs.

For years, scientists have sought to harness controllable nuclear fusion, the same power that lights the sun and stars. This latest experiment relied on a tiny crystal to generate a strong electric field. While falling short as a way to produce energy, the method could have potential uses in the oil-drilling industry and homeland security, said Seth Putterman, one of the physicists who did the experiment at the University of California, Los Angeles.

The experiment's results appear in today's issue of the journal Nature.

Previous claims of tabletop fusion have been met with skepticism and even derision by physicists. In 1989, B. Stanley Pons of the University of Utah and Martin Fleischmann of Southampton University in England shocked the world when they announced that they had achieved so-called cold fusion at room temperature. Their work was discredited after repeated attempts to reproduce it failed.

Fusion experts noted that the UCLA experiment was credible because, unlike the 1989 work, it didn't violate basic principles of physics.

"This doesn't have any controversy in it because they're using a tried and true method," said David Ruzic, professor of nuclear and plasma engineering at the University of Illinois at Urbana-Champaign. "There's no mystery in terms of the physics."

Fusion power has been touted as the ultimate energy source and a cleaner alternative to fossil fuels such as coal and oil. Fossil fuels are expected to run short in about 50 years.

In fusion, atoms are joined in a high-temperature process that frees large amounts of energy.

It is considered environment-friendly because it produces virtually no air pollution and does not pose the safety and long-term radioactive waste concerns associated with modern nuclear-power plants, where heavy uranium atoms are split to create energy in a process known as fission.

In the UCLA experiment, scientists placed a tiny crystal that can generate a strong electric field into a vacuum chamber filled with deuterium gas, a form of hydrogen capable of fusion. Then the researchers activated the crystal by heating it.

The resulting electric field created a beam of charged deuterium atoms that struck a nearby target. When some of the deuterium atoms in the beam collided with their counterparts in the target, they fused.

The reaction gave off an isotope of helium along with subatomic particles known as neutrons, a characteristic of fusion. The experiment did not, however, produce more energy than the amount put in. Commercial neutron generators work in a similar way. But the UCLA instrument was "remarkably low-tech" in comparison, Michael Saltmarsh, a retired physicist from the Oak Ridge National Laboratory in Tennessee, wrote in an accompanying article.

Putterman said future experiments will focus on refining the technique for potential commercial uses, including designing portable neutron generators that could be used for oil-well drilling or scanning luggage and cargo at airports.