Recent research published in the journal Nuclear Fusion has shed light on the complex interactions between fishbone instabilities and internal transport barriers (ITBs) in plasma within tokamak reactors, specifically the Experimental Advanced Superconducting Tokamak (EAST) in China. Led by Wanling Ge from the Key Laboratory of Materials Modification by Laser, Ion and Electron Beams at Dalian University of Technology, this study provides insights that could have significant implications for the future of nuclear fusion energy.
Fishbone instabilities, which are oscillations in plasma caused by energetic particles, and internal transport barriers, which help to confine plasma and improve stability, often occur together in tokamak experiments. The research team employed advanced simulations using the hybrid kinetic-MHD code M3D-K to explore how these phenomena interact. Their findings suggest that fishbone instabilities can generate a radial electric field, which may serve as a trigger for the formation of ITBs. This discovery is particularly important as ITBs enhance plasma confinement, a critical factor for achieving efficient nuclear fusion.
The study revealed that during the nonlinear stage of fishbone instability, a zonal electric field is induced, resulting in a strong E × B zonal flow. This flow is capable of suppressing microinstabilities that can disrupt plasma stability before the formation of an ITB, thereby facilitating its establishment. Wanling Ge noted, “This should account for ITB triggering,” highlighting the potential for fishbone instabilities to play a crucial role in stabilizing fusion reactions.
Once an ITB is formed, the equilibrium pressure gradient within the plasma increases, allowing fast ions from neutral beam injection to accumulate in the ITB region. This accumulation further modifies the plasma conditions, leading to changes in the bootstrap current density profile, which in turn stabilizes the fishbone mode. The research indicates that the distribution of fast ions around the ITB region broadens, contributing to the stabilization of these oscillations.
The implications of this research extend beyond theoretical physics; they present commercial opportunities for sectors involved in nuclear fusion technology. Enhanced understanding of plasma stability can lead to more efficient fusion reactors, which are seen as a potential solution for clean energy generation. As countries invest in fusion technology, advancements like those achieved in the EAST experiments could accelerate the development of commercially viable fusion power plants.
As the global energy landscape seeks sustainable solutions, the findings from Wanling Ge and her team highlight a promising avenue for improving plasma confinement and stability in fusion reactors. This research not only enriches our understanding of plasma physics but also paves the way for future innovations in clean energy, reinforcing the importance of continued investment in fusion research.
