Splitting and combining atoms both produce heat and energy. We’re already familiar with fission, as this is the process used in nuclear reactors and atomic bombs. It involves a large atom splitting into two or more smaller ones. Fusion, just as its name implies, involves fusing, or, combining, two or more atoms into a larger atom. This process powers the Sun and the stars. The materials used for fusion have shorter half-lives than fission, thus the process doesn’t carry the same safety risks as fission.
To make fusion happen, it requires very high temperatures – 100 million degrees Celsius! Isotopes of hydrogen (called deuterium and tritium) get ionized and the massive gravitational pull of the Sun compresses these atoms into helium, releasing bursts of energy which get transmitted as light and heat in the solar system. For decades now, scientists have pursued developing fusion on Earth. One way to do it is through magnetic confinement, where strong magnetic fields hold the ionized atoms together, and heating from microwaves and other energy sources drives the fusion process. Another way is through zapping hydrogen isotopes with hundreds of lasers to generate the temperatures needed. This is what was recently done at the US National Ignition Facility in California.
Earlier this week, scientists confirmed results: ignition was achieved, which means that the nuclear reaction that was created generated more energy than it consumed. In fact, about 50% more! Since research into nuclear fusion began in the 1950s, this is the first time that this has been achieved. What’s the importance, in the big-picture? It could solve our energy needs because, if sustainable, the energy source would be inexhaustible. Fusion could also solve the climate crisis because it would significantly reduce our dependence on fossil fuels. However, this is a long way off as scientists have only, thus far, successfully achieved ignition once. It would need to be reproducible, as well as scalable, to be a viable alternative. This means that we should continue our efforts to reduce global carbon emissions while also continuing this important research.
photo: by Ulyana Peña, Fermi lab, Illinois, USA