Collaborative Research in Magnetic Fusion Energy Science on Long-Pulse International Stellarator Facilities | DE FOA 0002429

Opportunity Information: Apply for DE FOA 0002429

The Department of Energy Office of Science, through its Fusion Energy Sciences (FES) program, issued this funding opportunity to support U.S.-led experimental research on two major long-pulse, superconducting stellarator facilities located overseas: Wendelstein 7-X (W7-X) in Germany and the Large Helical Device (LHD) in Japan. The central aim is to fund U.S. teams to plan, execute, and analyze experiments in close collaboration with the host institutions, using these unique facilities to address high-impact magnetic fusion science and technology questions that are difficult or impossible to tackle elsewhere. This opportunity sits within the FES Burning Plasma Science Long Pulse portfolio, which is specifically meant to leverage international partnerships and world-leading devices to push the frontiers of steady-state magnetic confinement research.

A key motivation behind the call is the growing U.S. interest in credible pathways to a fusion pilot plant, including concepts that could deliver electricity with as low a capital cost as possible. The opportunity references major community and strategic guidance, including a National Academies report advocating a coordinated national program toward a compact pilot plant, and an APS Division of Plasma Physics community planning process that identified stellarators as a potentially attractive route to that goal. In practical terms, applicants are expected to explain how their proposed work helps advance stellarators toward pilot-plant relevance, not just as basic plasma physics experiments but as integrated systems that must sustain high performance in steady-state conditions.

The DOE also points to its longer-term program strategy, including the Office of Science "Fusion Energy Sciences Program: A Ten-Year Perspective" (2016), which emphasizes applying mature U.S. expertise to collaborative research on long-pulse superconducting facilities. The United States has already invested heavily in W7-X hardware and diagnostics, particularly targeting edge/divertor science and improved understanding of core confinement. This FOA is designed to sustain and deepen the U.S. role in W7-X operations while also expanding targeted collaborations with LHD to strengthen understanding of three-dimensional (3D) confinement physics across different helical device designs.

Proposed projects must align with the near-term (roughly three-year) research priorities of W7-X and LHD, with five topical areas highlighted. First is "compatible core-edge solutions," reflecting that long-pulse operation requires the core plasma performance and the plasma-facing components/divertor to work together without unacceptable heat loads or impurity problems. W7-X employs an island divertor and is upgrading divertors and plasma-facing components to enable long pulses; DOE is looking for research that helps understand, optimize, and fully exploit this upgraded capability. In parallel, LHD is testing a closed helical divertor, and the FOA encourages work that leads to validated physics models for 3D divertor configurations, which are essential for predicting heat and particle exhaust in stellarators.

Second is "understanding limits," prompted by early W7-X operation that revealed regimes with improved ion confinement. DOE is interested in research that characterizes these regimes, learns how to access and control them, and explores how far they can be extended. This area also includes studying and mitigating factors that can degrade performance or complicate plasma-wall interaction, such as bootstrap current effects and magnetic field errors that can alter the plasma-divertor interface in W7-X. Projects that improve understanding and control of these phenomena are directly responsive.

Third is "exploiting U.S. hardware investments," which reflects a practical expectation that U.S. teams will help extract scientific value from instruments and components the U.S. has funded. The FOA notes a new steady-state pellet injector system planned for W7-X to support long-pulse fueling, along with U.S.-supported capabilities such as trim coils for correcting low-order field errors, a divertor scraper element, infrared and visible imaging, an x-ray imaging crystal spectrometer, fluctuation diagnostics, and neutral pressure measurements. The call seeks research that complements broader U.S. stellarator efforts through operational scenario development, data analysis, and modeling, especially in areas like magnetohydrodynamics and 3D magnetic structure, boundary and scrape-off-layer physics, and neoclassical and turbulent transport.

Fourth is "long-pulse, high power operation," recognizing that as W7-X moves into upgraded, higher-power, longer-duration regimes, new integrated challenges become central. These include reliable core fueling (including pellet fueling strategies), controlling and spreading heat flux to protect plasma-facing components, and sustaining stable operation over long time scales. DOE is explicitly seeking research that enables successful high-power, long-pulse operation by improving understanding, operational control, and predictive capability for these coupled processes.

Fifth is "comparative studies on long-pulse helical devices," emphasizing that W7-X and LHD differ substantially in design and operating approach, creating a valuable opportunity to separate general stellarator physics from machine-specific effects. Comparative work can test the portability of confinement and exhaust models, clarify the role of magnetic configuration details, and strengthen confidence in the physics basis needed for future pilot-plant design choices. DOE signals strong interest in proposals that deliberately exploit the two-machine ecosystem to build more robust, generalizable understanding.

On the collaboration and access side, the FOA specifies the required frameworks. Research on W7-X is expected to occur under the established Project Agreement between the Max Planck Institute for Plasma Physics (IPP) and DOE. Research on LHD is to be carried out under the International Energy Agency Stellarator Heliotron Technology Collaboration Program, and organizations without existing agreements with Japan's National Institute for Fusion Science (NIFS) may need to establish individual task agreements. Applications must include letters of support from the host institutions for the proposed collaborative work: IPP for W7-X and NIFS for LHD, underscoring that projects need to be well integrated with the facilities' plans and operational realities.

From an administrative standpoint, the opportunity (DE-FOA-0002429) was issued by the DOE Office of Science as a discretionary grant program under CFDA 81.049. Eligibility was listed as unrestricted (open to any entity type, subject to any additional text-based eligibility conditions). The FOA anticipated around six awards, with an award ceiling of $700,000. The original posting date was November 18, 2020, with an original application deadline of January 25, 2021.

• The Department of Energy - Office of Science, Office of Science in the science and technology and other research and development sector is offering a public funding opportunity titled "Collaborative Research in Magnetic Fusion Energy Science on Long-Pulse International Stellarator Facilities" and is now available to receive applicants.
• Interested and eligible applicants and submit their applications by referencing the CFDA number(s): 81.049.
• This funding opportunity was created on Nov 18, 2020.
• Applicants must submit their applications by Jan 25, 2021. (Agency may still review applications by suitable applicants for the remaining/unused allocated funding in 2026.)
• Each selected applicant is eligible to receive up to $700,000.00 in funding.
• The number of recipients for this funding is limited to 6 candidate(s).
• Eligible applicants include: Unrestricted (i.e., open to any type of entity above), subject to any clarification in text field entitled Additional Information on Eligibility.

Apply for DE FOA 0002429

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