Recent research published in ‘Nuclear Fusion’ has unveiled significant insights into the behavior of edge-localized modes (ELMs) in long-pulse high-confinement mode (H-mode) plasmas, particularly within the Experimental Advanced Superconducting Tokamak (EAST) in China. The study, led by Y.F. Wang from the Institute of Plasma Physics at the Hefei Institutes of Physical Science, highlights how the transition from small to large ELMs is closely linked to changes in separatrix density, which is influenced by fuel recycling processes during long-duration plasma operations.
During the 2017 EAST campaign, researchers noted a consistent pattern where large ELMs emerged as the separatrix density decreased. This phenomenon is attributed to a reduction in fuel recycling over time, which impacts the stability of the plasma. The study indicates that the relationship between ELM instability and separatrix density is a balancing act between stabilizing and destabilizing forces in the plasma’s edge region. Specifically, “with a high separatrix density, the ideal ballooning mode can be destabilized near the separatrix,” leading to smaller ELMs.
The implications of this research are profound for the energy sector, particularly in the pursuit of fusion energy. ELMs are critical to the performance and stability of fusion reactors; managing their behavior can enhance the efficiency and safety of these systems. The findings suggest that by actively controlling fuel recycling—such as adjusting the location of the strike point on the divertor target—operators can significantly influence separatrix density and, consequently, the occurrence of large ELMs. As Wang noted, “the mitigation of large ELMs is strongly correlated with the significant increase in separatrix density,” which could pave the way for more stable plasma confinement in future fusion reactors.
Furthermore, this research opens up commercial opportunities in the development of advanced plasma control technologies. By leveraging insights from simulations like SOLPS-ITER, which predict ionization sources in the scrape-off layer, companies could innovate in reactor design and operational strategies, potentially leading to more viable fusion energy solutions.
As the global energy landscape increasingly seeks sustainable and clean energy sources, advancements in fusion technology, informed by studies like this one, could prove pivotal. The quest for fusion energy, while still in its developmental stages, holds promise for providing a nearly limitless and environmentally friendly energy source.
For more details about the research and its implications, you can refer to the Institute of Plasma Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences at lead_author_affiliation.
