Researchers at China’s Experimental Advanced Superconducting Tokamak (EAST), nicknamed the “artificial sun,” have demonstrated a notable nuclear fusion milestone by sustaining plasma densities well above the long-standing Greenwald Limit, tells Live Science. For decades, this empirical cap served as a benchmark for plasma instability in tokamak reactors. By carefully controlling fuel pressure and applying targeted microwave heating, the team achieved stable plasma at densities 1.3 to 1.65 times higher than that limit, confirming the existence of a theoretical “density-free regime” in which plasma remains stable even as density increases.
The breakthrough is significant because higher plasma density increases the likelihood of fusion reactions, stepping toward conditions needed for net energy gain. EAST’s success builds on earlier work that has steadily pushed operational boundaries in magnetic confinement fusion. Although exceeding the Greenwald Limit is not the first instance of surpassing it globally, the controlled approach at EAST validates theoretical models that could inform next-generation fusion devices.
The experiments draw on the plasma-wall self-organization theory, which describes how careful management of interactions between plasma and reactor walls can sustain stability at extreme conditions. The research appears in Science Advances and is expected to influence international fusion efforts, including contributions to the ITER project in France, where larger fusion experiments are planned.
Despite the progress, fusion energy remains experimental. Current reactors, including EAST, still use more energy than they generate. Practical fusion power plants that produce net electricity are years away, but this achievement sharpens the scientific roadmap. As climate and energy demands grow, advances like this will shape the long-term prospects for carbon-free, high-density energy sources.