Chinese scientists have achieved a historic breakthrough in nuclear fusion research, successfully pushing plasma density beyond a theoretical limit that has constrained fusion experiments for decades. The Experimental Advanced Superconducting Tokamak, known as China's artificial sun, reached the long-theorized density-free regime where plasma remains stable at extremely high densities without triggering destructive instabilities.
The research team at the Hefei Institutes of Physical Science demonstrated that plasma density can be pushed well past the Greenwald limit, an empirical boundary that has traditionally marked the point where fusion experiments become unstable and must be terminated. By carefully controlling initial fuel gas pressure and applying electron cyclotron resonance heating during startup phases, researchers reduced impurity buildup and energy losses that typically cause plasma disruptions.
According to Professor Ping Zhu from Huazhong University of Science and Technology, the breakthrough relies on plasma-wall self organization theory. In this state, stability emerges when interactions between the plasma and reactor walls reach a carefully balanced equilibrium where physical sputtering dominates plasma behavior. The fusion fuel was heated to approximately 150 million kelvin, more than ten times hotter than the core of the Sun.
The findings, published in Science Advances on January 1, 2026, represent a significant step toward making fusion power a practical reality. Professor Zhu stated that the results suggest a practical and scalable pathway for extending density limits in tokamaks and next-generation fusion devices, bringing the goal of fusion ignition substantially closer. Associate Professor Ning Yan from the Hefei Institutes contributed to the groundbreaking research.
Fusion energy has long been considered the holy grail of clean power generation, promising virtually unlimited energy with minimal environmental impact. Unlike nuclear fission used in current power plants, fusion produces no long-lived radioactive waste and carries no risk of meltdown. This breakthrough addresses one of the fundamental challenges that has prevented scientists from achieving sustained fusion reactions, potentially accelerating the timeline for commercial fusion power plants that could help address global energy demands and climate change.
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