In the quest to harness the power of fusion energy, researchers are tackling one of the most daunting challenges: managing the intense heat and particle exhaust from fusion reactions. A recent study published in the journal Nuclear Materials and Energy, titled “Exhaust assessment of a European Volumetric Neutron Source (EU-VNS) using SOLPS-ITER,” sheds light on potential solutions that could revolutionize the energy sector.
At the heart of this research is the European Volumetric Neutron Source (EU-VNS), a small-scale fusion device designed to generate a neutron wall load of about 0.5 MW per square meter. This device is crucial for qualifying tritium breeding blankets early in the development process, supporting the EU’s demonstration fusion power plant, EU-DEMO. The goal is to mitigate the risk of late-stage testing for essential nuclear technologies.
The EU-VNS, with a major radius of 2.5 meters, is driven by a deuterium beam targeting a tritium source, producing approximately 30 MW of fusion power. However, the device must also handle the exhaust of helium particles and dissipate significant energy from the auxiliary power required, which predominantly enters the edge of the plasma. This is where the work of lead author Dr. S. Wiesen, affiliated with the Dutch Institute for Fundamental Energy Research (DIFFER) in Eindhoven, the Netherlands, and the Forschungszentrum Jülich in Germany, comes into play.
Dr. Wiesen and his team used the SOLPS-ITER code, a sophisticated simulation tool, to assess the exhaust capabilities of the EU-VNS. Their findings indicate that argon seeding can create a finite operational window for the divertor, the component responsible for exhausting heat and particles. This window allows for the avoidance of core dilution by helium and reduces the peak heat-flux density below 10 MW per square meter, a critical threshold for maintaining the device’s integrity.
One of the key challenges is sustaining good core performance to produce the required amount of fusion neutrons. The researchers found that by maintaining a Greenwald fraction of approximately 0.5 and keeping the total tritium throughput at about half the ITER value, they could meet the extra constraint of Zeff (the effective charge number) being less than 2-3. “This balance is crucial for ensuring that the core plasma remains hot and dense enough to produce the necessary fusion reactions,” Dr. Wiesen explained.
The study also suggests that the operational window for the EU-VNS can be further enlarged by exploring other seeding species, such as krypton, and refining the balance between pellet and gas fueling. Integrated core-edge modeling could provide additional insights and optimizations.
The implications of this research are far-reaching. As the world seeks sustainable and clean energy sources, fusion power holds immense promise. The ability to efficiently manage heat and particle exhaust is a critical step towards making fusion energy a viable commercial option. The insights gained from this study could inform the design and operation of future fusion devices, bringing us closer to a future where fusion power is a mainstream energy source.
The research, published in Nuclear Materials and Energy, which translates to Nuclear Materials and Energy in English, marks a significant advancement in the field of fusion energy. As Dr. Wiesen and his team continue their work, the energy sector watches with anticipation, eager to see how these findings will shape the future of fusion power. The journey to commercial fusion energy is long and complex, but with each breakthrough, we inch closer to a future powered by the same forces that drive the stars.
