In what they're calling an incremental advance, the researchers report using 192 lasers to compress a pellet of fuel as a step toward creating a controlled fusion-energy reaction by mimicking the interior of the sun inside a laboratory.
There's a long way to go before a functioning fusion reactor can run on a common form of hydrogen found in seawater, creating massive amounts of energy while emitting minimal nuclear waste, they said.
What was achieved was not fusion "ignition," scientists at the Lawrence Livermore National Laboratory said, since their experiment required much more energy on the front end from all the laser shots than came out the back end. Still, when briefly compressed by the laser pulses, the isotopes in the fuel pellet fused, generating new particles and heating up the fuel further and generating still more nuclear reactions, particles and heat, they reported in the journal Nature.
The effect -- known as "alpha heating" -- is an important goal in fusion research, researchers not involved in the Livermore work said.
"It's the first sign that they're getting what we call self-heating," Stewart Prager of the Princeton Plasma Physics Laboratory in New Jersey told the Washington Post.
He said he's optimistic about achieving fusion energy in the long run.
"In 30 years, we'll have electricity on the grid produced by fusion energy -- absolutely," Prager said. "I think the open questions now are how complicated a system will it be, how expensive it will be, how economically attractive it will be."