Insider Brief
- The Stellaris design leverages high-temperature superconductors (HTS) to generate stronger magnetic fields while maintaining the steady-state operation benefits of stellarators, offering an inherently stable confinement system compared to tokamaks.
- The study suggests that by combining a quasi-isodynamic (QI) magnetic field structure with HTS technology, Stellaris could achieve a viable fusion power plant design with improved energy efficiency and reduced operational risks.
- If successful, Stellaris could provide an alternative to tokamak-based fusion reactors, with the potential for lower costs, reduced maintenance complexity, and accelerated commercial deployment.
A team of researchers led by Proxima Fusion has introduced a new stellarator design, Stellaris, that aims to overcome the engineering and physics challenges of fusion power plants. The study, published in Fusion Engineering and Design, presents a high-field quasi-isodynamic stellarator that integrates advances in superconducting magnets and computational optimization to improve plasma stability and confinement.
“For the first time, we are showing that fusion power plants based on QI-HTS stellarators are possible,” said Dr. Jorrit Lion, Co-Founder and Chief Scientist of Proxima Fusion, in a statement. “The Stellaris design covers an unparalleled breadth of physics and engineering analyses in one coherent design. To make fusion energy a reality, we now need to proceed to a full engineering design and continue developing enabling technologies.”
The Stellaris design leverages high-temperature superconductors (HTS) to generate stronger magnetic fields while maintaining the steady-state operation benefits of stellarators. Unlike tokamaks, which require large plasma currents and are prone to disruptions, stellarators offer an inherently stable confinement system.
The study suggests that by combining a quasi-isodynamic (QI) magnetic field structure with HTS technology, Stellaris could achieve a viable fusion power plant design with improved energy efficiency and reduced operational risks.
According to the study, the Stellaris concept achieves a peak fusion power of approximately 2.7 gigawatts and a projected electrical output of around 1 gigawatt. This design represents a significant performance leap over previous stellarator models, including Wendelstein 7-X (W7-X), which operates at much lower field strengths.
“Our results demonstrate that a coherent set of trade-offs between physics and engineering constraints can lead to a compelling stellarator design, suited for power plant applications,” the researchers write in their paper.
If successful, Stellaris could provide an alternative to tokamak-based fusion reactors, such as ITER, which have dominated fusion research. Stellarators do not require the same level of active control systems, reducing maintenance and operational complexity. Additionally, the study emphasizes that improved confinement and reduced fast particle losses make the design a strong candidate for commercial fusion energy.
The integration of high-field magnets allows for a compact reactor with enhanced performance, potentially lowering costs and accelerating the timeline for fusion energy deployment. However, the design still requires extensive experimental validation. The researchers anticipate that their findings will motivate greater focus on QI stellarators within both public and private fusion research programs.
Methods
The research team required advanced computational optimization techniques to refine the Stellaris configuration. Their approach focused on improving neoclassical transport, stabilizing plasma equilibrium and optimizing the positioning of superconducting magnets to balance engineering feasibility with plasma performance.
By building on lessons from W7-X and other stellarator experiments, the researchers designed a system that minimizes fast particle losses and enhances magnetic confinement. The device features modular coils with a minimized toroidal plasma current and a magnetic island chain at the edge, allowing for an island divertor — a method to control plasma exhaust. The study also analyzed factors such as first-wall cooling, divertor considerations, neutron shielding, and remote maintenance strategies.
The team used the SFINCS code to model neoclassical transport and the COBRAVMEC code to analyze stability under varying plasma conditions. Their results indicate that Stellaris can maintain stable confinement while achieving a volume-averaged plasma beta of approximately 2.76%, a key metric in fusion performance.
“When Proxima started its journey, the founders said, ‘This is possible, we’ll prove it to you.’ And they did,” said Ian Hogarth, a Partner at Plural, one of Proxima Fusion’s earliest investors, in a statement. “Stellaris positions QI-HTS stellarators as the leading technology in the global race to commercial fusion.”
Limitations
Despite its promising characteristics, Stellaris is still in the conceptual phase. The researchers acknowledge several uncertainties, including the scalability of their design and the long-term stability of the proposed magnetic confinement system. Additionally, the study relies on computational models rather than experimental validation, meaning that real-world factors could introduce unforeseen challenges.
Another limitation is the need for a robust tritium fuel cycle, a major hurdle for all fusion concepts. The researchers estimate that the reactor would require approximately 417 grams of tritium per day, necessitating efficient breeding technologies to sustain operation.
The study also notes that while stellarators avoid tokamak-like plasma disruptions, they introduce their own set of engineering challenges, particularly in maintaining the precise magnetic field configurations needed for optimal performance. Future research will need to address how to construct and maintain these intricate magnetic structures in a cost-effective manner.
Future Directions
The next steps for Stellaris include further refinement of its engineering design and experimental validation of its key principles. The researchers propose building an intermediate-step device to test its viability before scaling up to a full commercial power plant.
Proxima Fusion aims to collaborate with existing stellarator research programs, such as those at the Max Planck Institute for Plasma Physics, to further validate and refine the concept. The team also highlights the importance of exploring high-confinement operational regimes, which could improve the reactor’s performance beyond current predictions.
Ultimately, Stellaris represents a new avenue in fusion energy research. If its design proves viable, it could provide a long-term path to stable, commercially viable fusion power without the drawbacks of tokamaks. While significant challenges remain, the study underscores the growing role of stellarators in the pursuit of fusion energy.
By integrating advances in stellarator optimization and high-field magnet technology, the researchers believe Stellaris could offer a realistic path forward for commercial fusion power — and should be the focus of more intense research.
“We anticipate that this work will motivate greater focus on QI stellarators, in both publicly and privately funded research,” the team writes.
Proxima Fusion spun out of the Max Planck Institute for Plasma Physics (IPP) in 2023 to build the first generation of fusion power plants using QI-HTS stellarators. Proxima has assembled scientists and engineers from leading companies and institutions including the IPP, MIT, Harvard, SpaceX, Tesla, and McLaren.
In addition to Proxima, research institutions involved in the study included Max Planck Institute for Plasma Physics, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, the University of Wisconsin-Madison and Karlsruhe Institute of Technology (KIT).
