Scientists one step closer to fusion energy as US lab hits new milestone

18 Aug 2021

Image: © peshkov/

A US experiment generated more than 1.3 megajoules of fusion energy, representing a leap forward in realising the crucial moment of ignition.

Researchers at the Lawrence Livermore National Laboratory (LLNL) have taken a significant step towards sustained fusion energy on Earth, as a recent lab experiment smashed its previous energy output records from earlier this year.

While the results have yet to be peer reviewed, early analysis of the data shows a yield of more than 1.3 megajoules of energy. This would represent eight times the output from previous experiments in spring of 2021, and 25 times the yield of the facility’s achievement in 2018.

What is nuclear fusion?

Fission and fusion reactions both release energy but rely on opposite mechanisms. Fission is what goes on when atoms are split and has been used in nuclear reactors and bombs, while fusion is what occurs when atoms are joined together, for example, in the sun. While fission is easier to achieve and harness, fusion has the potential to release vast amounts of clean energy.

This is one of the objectives scientists at the National Ignition Facility (NIL) at LLNL are working towards. Ignition in fusion energy is the point where the energy being produced exceeds that being lost to cooling, creating a self-sustaining feedback loop of clean energy that no longer needs external energy input.

‘Gaining experimental access to thermonuclear burn in the laboratory is the culmination of decades of scientific and technological work stretching across nearly 50 years’

Researchers around the world have made this their goal, as it has the potential to create clean, near limitless energy. While the researchers at LLNL aren’t near realising this point, the breakthrough on 8 August could bring humanity one step closer to that achievement.

“This result is a historic step forward for inertial confinement fusion research, opening a fundamentally new regime for exploration and the advancement of our critical national security missions,” said LLNL director Kim Budil.

“It is also a testament to the innovation, ingenuity, commitment and grit of this team and the many researchers in this field over the decades who have steadfastly pursued this goal.

“For me it demonstrates one of the most important roles of the national labs – our relentless commitment to tackling the biggest and most important scientific grand challenges and finding solutions where others might be dissuaded by the obstacles.”

Tiny atoms and a laser

The experiment was carried out by using a focusing laser at NIF, which is the size of three American football fields. This laser is focused towards deuterium and tritium (isotopes of hydrogen) atoms frozen inside of a cylindrical x-ray ‘oven’.

This produces a hot spot the diameter of a human hair but will generate more than 10 quadrillion watts of fusion power in 100 trillionths of a second, primarily in the form of high-energy neutrons.

“Gaining experimental access to thermonuclear burn in the laboratory is the culmination of decades of scientific and technological work stretching across nearly 50 years,” said Los Alamos National Laboratory director Thomas Mason.

“This enables experiments that will check theory and simulation in the high-energy density regime more rigorously than ever possible before and will enable fundamental achievements in applied science and engineering.”

The lab stated that plans for repeats of this experiment are well underway but will take several months before they are ready.

Sam Cox was a journalist at Silicon Republic covering sci-tech news