Here’s what you’ll learn when you read this story:
- The Wendelstein 7-X stellarator in Germany has broken the record for plasma duration in a nuclear fusion reactor.
- Fusion reactions were sustained at high performance levels for 43 seconds, which is a major breakthrough in plasma physics.
- Unlike nuclear fission (which involves uranium), nuclear fusion only needs hydrogen ions and produces no toxic waste.
Nuclear energy as we know it today is generated through fission—the process of splitting atomic nuclei, which produces electricity without emitting greenhouse gases. The problem? Fission also creates radioactive waste as a byproduct of using uranium fuel.
That’s where nuclear fusion—or, at least, the promise of it—comes in.
Nuclear fusion is the same process that powers stars, like our Sun. Inside a star, hydrogen nuclei slam together under intense pressure and heat, fusing into helium and releasing a huge burst of energy. Scientists have long wanted to recreate fusion on Earth because it could deliver clean, virtually limitless power with no carbon emissions and much less radioactive waste than today’s nuclear plants.
Fusion reactors are still very much in the experimental stage, and scientists mostly focused on developing a kind of reactor called a tokamak, which uses magnetic coils to confine plasma in a donut-shaped chamber by generating a magnetic field. But the other serious design contender is called a stellarator.
Stellarators are more complex than tokamaks—especially when it comes to their magnetic coils—but they’re also more flexible. They can sustain plasma with less power and have design features that make controlling that plasma easier. The Wendelstein 7-X stellarator in Germany is one such monster, and it recently smashed a record in ... well, atom smashing.
In a recent experiment, researchers at the Max Planck Institute for Plasma Physics sustained a stable plasma reaction in the Wendelstein 7-X for 43 seconds, reaching the “triple product” performance level that’s required for viable nuclear fusion and achieving the all-time best results for any stellarator.
Maybe 43 seconds doesn’t sound like much, but it’s now the longest plasma duration ever in nuclear fusion, including tokamaks. Previously, the now-defunct JT60U Tokamak in Japan and the JET European Tokamak in the U.K—which boasted triple the plasma volume—held the records for plasma duration.
The triple product measures how close a fusion reactor is to reaching self-sustaining ‘breakeven’ energy production levels—the point at which a reactor produces more energy than it consumes. The three factors that go into the triple product are the density of ionized particles flowing through hot plasma, the temperature of ions being fused, and energy confinement time (how long it takes for heat to escape plasma that’s not heated again). Longer confinement times mean better insulation.
Unlike fission reactors, which use heavy elements such as uranium, fusion reactors rely on lighter elements (like the hydrogen ions deuterium and tritium), which help them avoid creating toxic nuclear waste.
The fuel injector for Wendelstein 7-X was created exclusively for this stellarator by scientists at the U.S. Department of Energy’s Oak Ridge National Laboratory (ORNL), which has also been instrumental in advancing other types of reactors. Several European laboratories—including the Center for Energy, Environmental and Technological Research (CIEMAT) in Spain and Budapest’s HUN-REN Center for Energy Research—contributed to the development of the fuel pellets.
As plasma was heated with microwaves over those record-breaking 43 seconds, the fuel injector provided the stellarator with 90 pellets of frozen hydrogen ions. The microwave heating system used electron cyclotron resonance—the most effective method for fusion, which uses electromagnetic waves to heat and ionize plasma to temperatures that (in this case) reached a scorching 30 million degrees Celsius (about 54 million degrees Fahrenheit). Because success depended on balancing heating with pulses of incoming fuel, the pellet injector was programmed with automatic pulse rates, which is an unprecedented move.
“The new record is a tremendous achievement by the international team. It impressively demonstrates the potential of Wendelstein 7-X,” Prof. Dr. Thomas Klinger of the Max Planck Institute for Plasma Physics said in a press release. “Elevating the triple product to tokamak levels during long plasma pulses marks another important milestone on the way toward a power-plant-capable stellarator.”
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Elizabeth Rayne is a creature who writes. Her work has appeared in Popular Mechanics, Ars Technica, SYFY WIRE, Space.com, Live Science, Den of Geek, Forbidden Futures and Collective Tales. She lurks right outside New York City with her parrot, Lestat. When not writing, she can be found drawing, playing the piano or shapeshifting.
