Recent research from the MAST-Upgrade tokamak has unveiled groundbreaking insights into the behavior of Alfvén eigenmodes (AEs), which could have significant implications for the future of fusion energy. The study, led by M.B. Dreval from the Institute of Plasma Physics at the National Science Center in Ukraine, marks the first observations of deuterium beam-driven sub-cyclotron frequency range AEs, specifically the global Alfvén eigenmodes (GAEs). These findings could influence how we harness fusion energy, a potential game-changer in the quest for sustainable power.
In this study, researchers identified distinct sets of eigenmodes separated by approximately 200 kHz, with an intriguing lower frequency separation of around 10 kHz within each set. This pattern is not just a technical curiosity; it aligns with theoretical models of the Shear Alfvén continuum, suggesting that these modes are localized at critical points in the plasma. “Our observations are consistent with GAE modeling, providing a clearer understanding of how these eigenmodes behave under different plasma conditions,” Dreval noted.
The implications of these findings extend beyond academic interest. In low plasma current discharges, the researchers observed GAEs propagating against both the plasma current and the beam direction, which raises questions about the stability and efficiency of future fusion reactors. In higher plasma current discharges, the simultaneous observation of co-propagating and counter-propagating GAEs indicates a more complex interaction within the plasma, driven by the formation of second continuum minima. This complexity could lead to improved control mechanisms in fusion reactors, enhancing their performance and reliability.
The research also highlights the significance of safety factor profiles in shaping plasma behavior. In higher plasma current MAST-U discharges, very flat safety factor profiles create conditions conducive to the formation of these minima, located around half of the plasma radius. Such insights could inform the design of future tokamak systems, potentially leading to more efficient energy production.
As the energy sector increasingly turns to fusion as a viable alternative to fossil fuels, understanding the dynamics of AEs becomes crucial. Dreval emphasizes this point: “The ability to manipulate and understand these eigenmodes could be pivotal in advancing fusion technology.” With ongoing global efforts to develop cleaner energy sources, this research could pave the way for more stable and efficient fusion reactors, transforming the landscape of energy production.
The findings are published in the journal ‘Nuclear Fusion,’ which translates to ‘Nuclear Fusion’ in English. This research not only contributes to the scientific community’s understanding of plasma physics but also holds promise for the future of energy generation. For those interested in the details of this study, M.B. Dreval’s affiliation can be found at the Institute of Plasma Physics, National Science Center, Kharkov Institute of Physics and Technology.
