In a Huge First, Physicists May Have Found a Shortcut to Fusion Energy
NEWS | 15 October 2026
The Sun at the center of our own Solar System is a great advert for nuclear fusion: ultra-high temperatures and pressures combining to fuse hydrogen nuclei together into helium nuclei, releasing a huge amount of energy along the way. If we can get the same reactions happening on Earth, nuclear fusion has the potential to drive a revolution in abundant, carbon-free energy – but replicating a star inside a science lab is proving as challenging as you might expect. Now, researchers from Princeton University have published a study in Physical Review Letters that details how we might get to nuclear fusion more quickly. It outlines what is effectively a shortcut to something called ignition, where plasma can maintain the necessary heat levels through its own fusion reactions. Thankfully for the non-physicists amongst us, the researchers provide an analogy. If ignition is a valley behind a mountain range, then their new idea is to circumvent the mountains, rather than trying to get over the top of them. "A lot of companies want to climb the mountain head-on and spend enormous energy to get there," says physicist Luis Delgado-Aparicio. "Go around the peak instead. You reach the same place in a much smarter way, and you use far less energy." frameborder="0″ allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture; web-share" referrerpolicy="strict-origin-when-cross-origin" allowfullscreen> The study is based on an extension of the Lawson criterion. Developed in the 1950s, it sets down the framework and rules that a reactor needs to achieve ignition. Here, the researchers added four other factors to the calculations, covering spent fuel in the form of helium ash, plasma impurities from the reactor walls, radiation losses known as synchrotron radiation, and heat flowing out of the plasma. These effects on ignition have been studied before, but not together. The aim was to get a more realistic and accurate look at how a reactor should be configured. "When you leave these effects out, you say the design will work fine," says Masayuki Ono. "When you put them in, the picture changes, and it becomes quite important." The researchers were looking for what mathematicians call the Cordey saddle: the path to ignition (the valley beyond the mountains) that requires the least energy. The calculations showed that heating the plasma first, then adding density, is the best way to go, rather than the other way around. Other findings from the study models included indications that even a very small amount of tungsten can cause nuclear fusion to fail. As the metal is set to be used in the walls of several planned reactors, and it's so good at withstanding heat, the plasma will have to be well protected against it. The team also discovered some natural 'brakes' for nuclear fusion. Radiation and heat leakage could keep the plasma reactions stable, the models showed, though would also make ignition more difficult to begin with. "As fusion research advances from burning-plasma experiments toward reactor-scale power production, the present framework provides a timely foundation for evaluating ignition accessibility, stability, and performance in next-generation devices," write the researchers in their published paper. This study didn't involve any actual tests or experiments, but with multiple nuclear fusion reactors now being proposed and designed, the findings should give these power plants a greater chance of success – and potentially save a lot of development time and money. Experts are split on just how long it will take to get nuclear fusion reactors up and running – if it's possible to ever get there – but this research shows a viable route to the goal. Alongside other recent advances, it means we're closer than ever to nuclear fusion. "While more study is needed, we are excited by these results, and they suggest a clear path forward for future research in this area," says physicist Jonathan Menard. The research has been published in Physical Review Letters.
Author: David Nield.
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