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Dubbed China’s “artificial sun,” the Experimental Advanced Superconducting Tokamak (EAST) has broken fusion records. |Photo source: Zhang Dagang/VCG, from Getty Images
China’s nuclear fusion reactor, dubbed the “artificial sun,” blasts plasma beyond its usual operating range, thereby breaking major fusion limits and propelling humanity’s slow march toward near-limitless clean energy.
Experimental Advanced Superconducting Tokamak (EAST) maintains plasma – high energy The fourth state of matter – Remains stable at extreme densities, which was previously seen as a major obstacle to the development of nuclear fusion, according to one study statement Released by the Chinese Academy of Sciences.
Study co-lead author: “The findings suggest a practical and scalable pathway to extend the density limits of tokamak and next-generation combustion plasma fusion devices.” Zhu PingA professor at the School of Electrical and Electronic Engineering at the University of Science and Technology of China said in a statement.
nuclear fusion Offering nearly unlimited potential for clean energy. In other words, there is not much energy nuclear waste or climate warming greenhouse gas emissions Released by burning fossil fuels. The new findings were published in the journal Jan. 1 scientific progresscould bring our species closer to unlocking this energy source that some researchers claim we can harness within decades.
However, fusion technology has been in development for more than 70 years, and it remains largely an experimental science, with reactors often consuming more energy than they produce. Meanwhile, climate scientists are calling for further research Reduce greenhouse gas emissions Now with climate change This is already being felt around the world. Therefore, nuclear fusion is unlikely to be a practical solution to the current climate crisis, but it could power the world of the future.
Fusion reactors are designed to fuse two light atoms into one heavy atom using heat and pressure. By doing so, they generate energy in a similar way to the sun. However, the pressure of the Sun is much greater than that of Earth’s reactors, so scientists compensate by focusing hot plasma at much higher temperatures than the Sun.
China’s EAST is a magnetically confined reactor, also known as a tokamak device, designed to keep plasma burning for a long time. The reactor heats the plasma and uses powerful magnetic fields to trap it in a toroidal chamber. Tokamak reactors have yet to achieve fusion ignition, the point at which the fusion process becomes self-sustaining, but the EAST reactor has been increasing the amount of time it can do so. Maintaining a stable, highly confined plasma loop.
One obstacle facing fusion researchers is a density limit called the Greenwald limit, beyond which plasmas typically become unstable. This limitation is a problem because while higher plasma density enables more atoms to hit each other, thereby reducing the energy cost of ignition, instabilities can also disrupt the fusion reaction.
To overcome the Greenwald limit, EAST scientists carefully managed the interaction of the plasma with the reactor walls by controlling two key parameters at reactor start-up: initial fuel gas pressure and Electron cyclotron resonance heatingor the frequency at which electrons in a plasma absorb microwaves. The study shows that this allows the plasma to remain stable at extreme densities 1.3 to 1.65 times beyond the Greenwald limit, well above the tokamak’s typical operating range of 0.8 to 1.
This isn’t the first time Greenwald’s limits have been exceeded. For example, the U.S. Department of Energy’s DIII-D National Fusion Facility Tokamak in San Diego exceeded the limit In 2022 and 2024, researchers at the University of Wisconsin-Madison in Wisconsin announced that they had maintained a stable tokamak plasma at approximately 10 times Greenwald’s limit Use the experimental setup.
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However, the EAST breakthrough allowed researchers to heat a plasma for the first time to a previously theorized state called a “density-free state,” in which the plasma remains stable as density increases. The research is based on a method called Plasma wall self-organization (PWSO), which proposed that a density-free state is possible when the interaction between the plasma and the reactor walls is in a carefully balanced state, according to the statement.
Progress made by EAST and the United States will inform the development of new reactors. China and the United States are both part of this country International Thermonuclear Experimental Reactor (ITER) programme, a collaboration among dozens of countries to build The world’s largest tokamak device in France.
ITER will be another experimental reactor designed to create sustained fusion for research purposes, but may also pave the way for fusion power plants. The ITER reactor is expected to begin producing a full-scale fusion reaction in 2039.
