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How AI Is Used For Shadow Detection in Fusion Reactors

Predicting Heat Hotspots with Lightning Speed

Fusion reactors operate at extreme temperatures, making the identification of vulnerable surfaces essential for safe and efficient operation. A cutting-edge artificial intelligence tool, HEAT-ML, developed by Commonwealth Fusion Systems, Princeton Plasma Physics Laboratory (PPPL), and Oak Ridge National Laboratory, is transforming how researchers safeguard these powerful machines from heat damage.

The Critical Role of Magnetic Shadows

Inside fusion reactors like the SPARC tokamak, plasma is confined at temperatures exceeding those at the sun’s core. Some internal components are shielded from this intense heat by other structures, creating magnetic shadows

Quickly detecting these zones is vital for preventing the melting or deterioration of plasma-facing parts, which could otherwise lead to expensive repairs and operational delays.

  • Magnetic shadows shield certain areas from direct plasma heat using the reactor’s geometry and magnetic fields.

  • Accurate prediction of shadow zones supports the longevity and safety of critical reactor components.

  • Fast shadow detection allows operators to tweak plasma configurations on the fly, minimizing risks and downtime.

HEAT-ML: AI-Powered Speed and Precision

Traditional shadow-mapping with the HEAT toolkit could take half an hour for a single simulation, and even longer for intricate reactor designs. HEAT-ML, powered by a deep neural network trained on approximately 1,000 SPARC reactor simulations, slashes this time to mere milliseconds.

  • HEAT-ML functions as an AI surrogate, offering rapid and reliable shadow predictions.

  • It traces the magnetic field lines and instantly identifies which regions are protected by internal structures.

  • This leap in computational speed allows for more frequent design iterations and real-time operational adjustments.

Enhancing Fusion System Design and Safety

The initial focus of HEAT-ML was on 15 highly exposed tiles at the SPARC tokamak’s base, an area crucial to achieving the facility’s target of net energy gain by 2027. By simulating thermal impacts on these components, researchers can better ensure SPARC’s long-term performance and safety.

Currently, HEAT-ML is an optional feature within the original HEAT code, optimized for a specific exhaust region of SPARC. The development team plans to broaden its application, adapting the tool to account for the diverse forms and functions of fusion reactor parts across future systems.

Collaboration Drives Innovation

This project exemplifies the benefits of collaboration between academia, government, and industry. With support from the U.S. Department of Energy, HEAT-ML not only accelerates fusion research but also enables more intelligent and responsive reactor operations.

  • AI-driven shadow detection supports safer, more agile fusion reactor design and operation.

  • Real-time monitoring could lead to automated control strategies that prevent heat damage before it happens.

  • Ongoing advancements aim to generalize HEAT-ML for use in a wider range of reactor types and configurations.

Conclusion

HEAT-ML is a major milestone for fusion energy, demonstrating the transformative potential of AI in addressing complex physics challenges. As fusion technology advances toward commercial readiness, tools like HEAT-ML will be indispensable for building robust, efficient, and adaptable reactors.

Source: Princeton Plasma Physics Laboratory

How AI Is Used For Shadow Detection in Fusion Reactors
Joshua Berkowitz October 3, 2025
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