In the quest for sustainable and efficient energy, nuclear fusion remains a tantalizing frontier. Recent research from the Swiss Plasma Center (SPC) at Ecole Polytechnique Fédérale de Lausanne (EPFL) has shed new light on a critical aspect of this technology, potentially paving the way for more stable and efficient fusion reactors. The study, published in the journal Nuclear Fusion, focuses on understanding fast-ion losses during Edge Localised Modes (ELMs), a phenomenon that can significantly impact the performance of tokamak reactors.
Dr. J. Poley-Sanjuán, the lead author of the study, and his team have been investigating fast-ion losses using a unique Fast Ion Loss Detector (FILD) on the TCV tokamak. The FILD, equipped with a 128 Avalanche Photo Diodes (APDs) camera, provides unprecedented temporal resolution and velocity space information. This advanced capability allowed the researchers to observe and characterize fast-ion losses in the energy and pitch space during ELMs.
The study mimicked the ITER Baseline Scenario, replicating its shape and normalized plasma parameters. The researchers observed significant fast-ion losses, particularly before and during the ELM crashes induced by a 2/1 MHD instability localized at the plasma’s normalized radius, ρ ∼ 0.7. Notably, the fast-ion interaction with the plasma instability was found to be unconnected to the presence of the ELMs.
One of the most intriguing findings was the observed spread in both the fast-ion pitch and energy during the ELM crashes, reaching higher values (∼70 keV) than expected from the pre-ELM fast-ion population, generated by Neutral Beam Injection at ∼27 keV. This implies a fast-ion acceleration during the ELM’s crash, a phenomenon that warrants further investigation.
Dr. Poley-Sanjuán explained, “Understanding these fast-ion losses and their acceleration is crucial for optimizing the performance of fusion reactors. Our findings provide valuable insights into the dynamics of fast ions during ELMs, which can help in designing more efficient and stable tokamak reactors.”
The study also utilized full orbit neoclassical simulations to calculate the neoclassical fast-ion velocity space lost to the FILD and to quantify the neoclassical fast-ion losses. This comprehensive approach offers a deeper understanding of the underlying physics, which is essential for advancing fusion energy technology.
The implications of this research are significant for the energy sector. By improving our understanding of fast-ion behavior during ELMs, we can enhance the stability and efficiency of fusion reactors, bringing us closer to realizing the dream of clean, sustainable, and virtually limitless energy. As Dr. Poley-Sanjuán noted, “This work is a step towards unlocking the full potential of fusion energy, a critical component in the global transition to a low-carbon economy.”
The research, published in Nuclear Fusion, represents a significant advancement in the field of fusion energy. It highlights the importance of continued investment and innovation in this critical area, as we strive to meet the world’s growing energy demands in a sustainable and environmentally responsible manner. The findings not only contribute to the scientific community’s understanding of fast-ion dynamics but also offer practical insights that could shape the future of fusion energy technology.