Scientists working with China’s fully superconducting Experimental Advanced Superconducting Tokamak (EAST) have successfully reached a long-theorized “density-free regime” in fusion plasma experiments. In this state, the plasma remains stable even when its density rises far beyond traditional limits. The results, published in Science Advances on January 1, shed new light on how one of fusion energy’s most stubborn physical barriers might finally be overcome on the road to ignition.
The research was co-led by Prof. Ping Zhu of Huazhong University of Science and Technology and Associate Prof. Ning Yan of the Hefei Institutes of Physical Science at the Chinese Academy of Sciences. By developing a new high-density operating approach for EAST, the team showed that plasma density can be pushed well past long-standing empirical limits without triggering the disruptive instabilities that usually end experiments. This finding challenges decades of assumptions about how tokamak plasmas behave at high density.