The National Ignition Facility's fusion reactor uses 192 laser beams to focus laser light into a hot-spot the diameter of a human hair.

The National Ignition Facility's fusion reactor uses 192 laser beams to focus laser light into a hot-spot the diameter of a human hair. (Image credit: Science History Images/Alamy Stock Photo)

The researchers at the U.S. government lab say they have made a major scientific breakthrough. A small but consequential step in the race to unleash a near-limitless, zero-carbon alternate energy source to fossil fuels or conventional nuclear power plants has been achieved.

Physicists at the U.S. government-funded National Ignition Facility fired the world's most energetic laser beam to turn the hydrogen isotopes deuterium and tritium into a burning plasma

Since the 1940's, scientists have been trying to build practical methods of using nuclear fusion. By fusioning hydrogen atoms to make helium under extremely high pressures and temperatures, main-sequence stars convert matter into light and heat, generating enormous amounts of energy.

Nuclear fusion reactor breakthrough is significant, but light years away from being useful.

It's not easy to replicate the conditions found in the hearts of stars. A lot of energy is needed to transform fuel into a plasma, ignite it, and corral it with powerful magnetic fields. It has taken a long time and a lot of money to get here.

192 high-energy lasers converge on a target about the size of a peppercorn, heating the capsule of deuterium and tritium to over 3 million degrees Celsius. The undersecretary for Nuclear Security of the U.S. Department of Energy spoke at a news conference. A clean energy source that could change the world is the first tentative step we have taken.

The experiment, which took place in less than ten billionths of a second, streamed light particles into two ends of a cylinder inside the reactor's core and produced X-rays which heated a pellet of fuel into a burning plasma. The plasma burned for a long time before it died.

This is the most important step ever taken in this quest. For the first time, we have evidence of a fusion reaction producing a large amount of excess energy, according to a physics professor who wasn't involved in the experiment. There were doubts about the feasibility of a proof-of-principle experiment. The dissipated these have injected a lot of energy and optimism to push this forward and solve the technical issues still remaining.

A flurry of breathless news coverage excitedly heralds the dawn of unlimited, clean energy after the announcement was teased in a Financial Times article. While a net energy gain was observed between the lasers and the plasma at the reactor's heart, vastly more energy was utilized than given out across the entire reactor, scientists cautioned that this is just the first small step to achieving fusion commercial power.

"Unfortunately, it's not around the corner." Both public institutions and private companies will benefit from this result. We are talking of a few decades before we have a working nuclear reactor based on fusion.