Collaboration aims to boost efficiency and advance fusion power plant performance

Researchers at General Atomics (GA) are lending their expertise to address one of fusion energy’s greatest challenges: sustaining the fuel that powers fusion reactions. GA is collaborating with Japan’s National Institutes for Quantum Science and Technology (QST) and the European Union’s Fusion for Energy (F4E) to deliver a state-of-the-art diagnostic system to the world’s largest superconducting tokamak JT-60SA in Naka, Japan. This is among the first contributions to JT-60SA from an institution outside of Japan and Europe. The new diagnostic will measure how high-energy ions—particles that heat and sustain fusion plasma—move and interact inside a reactor, helping scientists design future commercial fusion power plants.

“Fusion has the potential to transform the global energy landscape with a safe, sustainable, and virtually limitless power source,” said Dr. Wayne Solomon, vice president of Magnetic Fusion Energy for the General Atomics Energy Group. “By delivering this advanced diagnostic system to JT-60SA, this collaboration will enable researchers to gain deeper insights that will be essential for optimizing performance in next generation fusion power systems.”

Fusion, the same process that powers the sun, requires heating plasma, a superheated gas, to more than 100 million degrees. In tokamaks, high-energy particles called fast ions are created by powerful heating beams and by the fusion reactions themselves. These fast ions act as sparks to keep the reactions going. However, those same ions also trigger waves and instabilities that push them off course and reduce the efficiency and performance of the reactor.

This international collaboration, established under the Broader Approach Agreement between the European Atomic Energy Community (Euratom) and Japan, includes activities designed to complement the ITER project, the world’s largest fusion experiment, and accelerate the development of fusion. Fusion for Energy (F4E)—the European Union organization responsible for managing Europe’s contribution to ITER, oversees Euratom’s share. Japan’s contribution is implemented by the National Institutes for Quantum and Radiological Science and Technology (QST), a national research institution established in April 2016 to advance quantum science and technology in an integrated and coordinated manner.

The project will utilize General Atomics’ Fast-Ion D-alpha (FIDA) diagnostics, a venture funded by the Department of Energy Fusion Energy Science program, to deliver high-resolution measurements of the fast ions’ behavior in JT-60SA’s plasma. By detecting subtle spectroscopic “fingerprints” produced when fast ions collide with a beam of neutral atoms, the system can map their location, speed, and response to plasma waves.

These measurements are directly compared with computer models, allowing researchers to validate simulations and identify instabilities that could affect reactor performance. Paired with advanced analysis codes, the diagnostic will effectively transform JT-60SA into a “fast-ion observatory,” providing critical insight into how operating conditions influence fusion plasmas. The results will form a foundation for designing and controlling next-generation fusion reactors, ensuring both stability and efficiency in future power plants.

“This work gives us the tools to move from best guesses to reliable prediction and controls,” said Christopher Muscatello, senior scientist for the Center for Advanced Diagnostics and Metrology at the General Atomics Energy Group. “By understanding how fast ions drive or respond to instabilities, we can design reactors that maximize performance, extend component lifetimes, and bring fusion energy closer to reality.”

General Atomics is a global leader in fusion technology development and manufacturing. Based in San Diego, the company operates the DIII-D National Fusion Facility for the U.S. Department of Energy—the nation’s largest operating tokamak. GA scientists and engineers also collaborate worldwide to design integrated systems, advanced materials, and custom-built components essential for advancing fusion energy.

About General Atomics

Since the dawn of the atomic age, General Atomics innovations have advanced the state of the art across the full spectrum of science and technology – from nuclear energy and defense to medicine and high-performance computing. Behind a talented global team of scientists, engineers, and professionals, GA��s unique experience and capabilities continue to deliver safe, sustainable, economical, and innovative solutions to meet growing global demands.

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