In a significant advancement for fusion energy, researchers have unveiled an innovative divertor design that could play a pivotal role in the Spherical Tokamak for Energy Production (STEP) project. This initiative, spearheaded by the United Kingdom Atomic Energy Authority (UKAEA), aims to harness the power of nuclear fusion as a viable energy source, potentially transforming the global energy landscape.
The STEP project stands out due to its compact design, featuring a major radius less than half that of conventional DEMO concepts. This smaller scale allows for a double-null divertor geometry, which is crucial for managing the intense heat and particle exhaust from plasma operations. As lead author S.S. Henderson from the UKAEA explains, “Our design leverages advanced simulations to optimize the plasma exhaust dynamics, ensuring that we can effectively handle the extreme conditions of fusion reactions.”
The research, published in the journal ‘Nuclear Fusion’, details how the team utilized a robust database of SOLPS-ITER simulations to map out the operational space for plasma exhaust. By validating simple models that predict key exhaust parameters, the researchers have streamlined the design process for the divertor, which is essential for maintaining the stability and efficiency of the fusion reactor.
One of the most promising findings from this work is the potential for achieving pronounced detachment during the burning phase of plasma operation. This state, characterized by peak heat loads that remain within engineering limits, is crucial for the longevity and safety of fusion reactors. Henderson notes, “We found that maintaining a divertor neutral pressure between 10 Pa and 15 Pa during the burning phase allows us to keep electron temperatures below 5 eV, which is a critical factor for effective plasma exhaust management.”
The research also highlights the importance of specific conditions in the scrape-off layer (SOL) to optimize performance. An argon concentration of approximately 3% is necessary, coupled with a core radiation fraction of 70%, driven by both intrinsic emissions and the injection of xenon-seeded fueling pellets. These findings not only provide insights into the operational parameters needed for successful plasma management but also indicate the potential for increased efficiency in auxiliary current-drive systems during the ramp-up phase.
The implications of this research extend beyond the laboratory. As the energy sector grapples with the urgent need for sustainable and clean energy sources, advancements like those proposed in the STEP project could pave the way for commercial fusion power plants. If successful, fusion energy could offer a near-limitless source of energy with minimal environmental impact, addressing both energy security and climate change challenges.
The work of Henderson and his colleagues at the UKAEA is a testament to the collaborative effort needed to turn fusion from a scientific dream into a practical reality. As they continue to refine their models and designs, the energy sector watches closely, hopeful that the future of energy could indeed be fusion. For more information about the research and the UKAEA’s initiatives, visit lead_author_affiliation.
