Researchers working on China’s Experimental Advanced Superconducting Tokamak (EAST) have succeeded in operating the reactor beyond a long-standing plasma density limit that has hindered fusion experiments for decades. This breakthrough could enhance the efficiency of future fusion reactors.
EAST, known as China’s “artificial sun,” is a tokamak facility in Hefei that employs superconducting magnets to confine ultra-hot plasma. Higher plasma density typically enables more fusion reactions. However, most tokamaks face instability when plasma density exceeds a certain threshold, causing disruptions as plasma interacts with the reactor walls. This threshold is widely recognised as the Greenwald limit.
The research team from the Institute of Plasma Physics at the Chinese Academy of Sciences identified that the density limit is closely related to impurities entering the plasma, particularly metal particles from the reactor’s inner walls. Tungsten, commonly used in fusion devices, was found to be a significant source of these impurities.
To tackle this, the scientists developed a model called Boundary Plasma-Wall Interaction Self-Organisation (PWSO). They tested this on EAST by combining electron cyclotron resonance heating with a pre-charged gas startup method, effectively reducing tungsten contamination at the plasma edge.
With impurity levels controlled, the plasma operated in what the researchers term a stable “density free zone,” surpassing the traditional density limit without causing disruptions. The experimental results closely matched the PWSO model’s predictions.
Published in Science Advances, these findings provide valuable insights for designing future high-density fusion reactors. Although commercial fusion power is still a long-term objective, this work addresses a key challenge in magnetic confinement fusion technology.
My name is Bhupendra Singh Chundawat. I am an experienced content writer with several years of expertise in the field. Currently, I contribute to Daily Kiran, creating engaging and informative content across a variety of categories including technology, health, travel, education, and automobiles. My goal is to deliver accurate, insightful, and captivating information through my words to help readers stay informed and empowered.
