Researchers achieve milestone on path toward nuclear fusion energy

US government scientists said on Wednesday they have taken an important step in the long trek toward making nuclear fusion - the very process that powers stars - a viable energy source for humankind.

Using the world's largest laser, the researchers coaxed fusion fuel for the first time to heat itself beyond the heat they zapped into it, achieving a phenomenon called a burning plasma that marked a stride toward self-sustaining fusion energy.

The energy produced was modest - about the equivalent of nine nine-volt batteries of the kind that power smoke detectors and other small devices. But the experiments at a Lawrence Livermore National Laboratory facility in California represented a milestone in the decades-long quest to harness fusion energy, even as the researchers cautioned that years of more work are needed.

The experiments produced the self-heating of matter in a plasma state through nuclear fusion, which is the combining of atomic nuclei to release energy. Plasma is one of the various states of matter, alongside solid, liquid and gas.