Chinese-American plasma physicist whose work on advanced tokamak scenarios at DIII-D and EAST has pushed the boundaries of high-performance steady-state operation — bridging two of the world's leading fusion programs.
Siye Ding has built a career that spans two of the world's most important tokamak programs, working at General Atomics' DIII-D National Fusion Facility in San Diego and at the Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP) in Hefei. This dual involvement has given him an unusual perspective on advanced tokamak physics, allowing him to apply insights gained on one machine to experiments on the other and to contribute to the development of operating scenarios that push both devices toward reactor-relevant performance.
His research focuses on a central challenge in fusion energy: how to sustain high-performance plasmas in steady state. While tokamaks can achieve impressive temperatures and pressures in brief pulses, a power plant must operate continuously, which requires self-generated plasma current, stable profiles, and acceptable heat exhaust — simultaneously and indefinitely. Ding's work addresses exactly this challenge.
At DIII-D, the largest operating tokamak in the United States, Ding has contributed to the development and refinement of advanced tokamak (AT) scenarios. These scenarios aim to maximize the ratio of plasma pressure to magnetic pressure (beta) while maintaining a large fraction of self-generated bootstrap current, reducing or eliminating the need for external current drive in steady-state operation.
DIII-D's extensive suite of heating, current drive, and diagnostic systems makes it an ideal platform for this work. Ding has utilized neutral beam injection, electron cyclotron heating, and sophisticated real-time plasma control to shape current and pressure profiles that achieve high confinement while maintaining MHD stability. His experiments have explored the boundaries of what is achievable in terms of normalized beta, confinement quality (H-factor), and pulse duration within the AT framework.[1]
Ding's work on EAST has focused on translating the high-performance scenarios developed on DIII-D into the long-pulse, fully superconducting environment that EAST provides. While DIII-D uses conventional copper magnets and operates in pulses of several seconds, EAST's superconducting magnets allow discharges lasting minutes to hours, testing whether advanced scenarios can be sustained over the timescales relevant to a power plant.
This translation is not straightforward. Long-pulse operation introduces challenges that short-pulse machines do not face: slow impurity accumulation, wall saturation, current profile evolution on resistive timescales, and the need for real-time feedback control over extended periods. Ding's work has addressed these challenges through careful scenario optimization and collaboration between the DIII-D and EAST teams.[2]
A recurring theme in Ding's research is the integration of multiple physics objectives into a single operating scenario. A fusion reactor must simultaneously achieve high temperature (for fusion reactions), high density (for sufficient reaction rate), good confinement (to retain energy), high bootstrap fraction (for steady-state operation), and manageable heat exhaust (to protect plasma-facing components). These requirements often conflict, and finding operating points that satisfy all of them is one of the hardest problems in fusion physics.
Ding has contributed to experiments that demonstrate simultaneous achievement of high beta, high confinement, high bootstrap fraction, and acceptable divertor conditions. These integrated demonstrations are more convincing than optimizing any single parameter in isolation, because they show that the physics does not preclude simultaneous satisfaction of reactor requirements.[3]
Ding's position between the American and Chinese fusion programs has made him a valuable conduit for technical knowledge exchange during a period of productive international collaboration. His experimental results inform scenario planning for both DIII-D and EAST, and contribute to the physics basis for future devices including ITER and CFETR. The advanced tokamak scenarios he has helped develop represent one of the leading candidates for the operating mode of a fusion power plant, making his work directly relevant to the commercial viability of tokamak-based fusion energy.
His career also reflects the increasingly international character of fusion research, where the complexity of the physics and the cost of the facilities demand collaboration that transcends national boundaries. The knowledge base that Ding and his colleagues are building — scenario by scenario, discharge by discharge — is a shared resource that will benefit whichever machine first achieves sustained fusion power.