Collaborative Research on International and Domestic Spherical Tokamaks | DE FOA 0001784

Opportunity Information: Apply for DE FOA 0001784

The Department of Energy Office of Science (Office of Science) released this discretionary grant opportunity, DE-FOA-0001784, titled "Collaborative Research on International and Domestic Spherical Tokamaks" to support research that advances the physics basis and reactor relevance of spherical tokamaks (STs). The program is motivated by results from upgraded ST devices showing that, as plasma collisionality is reduced, energy confinement in spherical tokamaks may improve more favorably than in conventional, higher-aspect-ratio tokamaks. If these empirical trends continue to hold, STs could offer a pathway to fusion reactor designs that are significantly more compact than traditional tokamak concepts, making them attractive for future power plants and pilot devices.

A central scientific theme of the opportunity is understanding how low-collisionality operation in spherical tokamaks is shaped by multiple tightly coupled factors: turbulent transport, density control, and wall conditioning techniques such as lithium coatings and boronization. The FOA highlights that these elements do not operate independently; instead, changes in wall conditions can alter neutral recycling and fueling, which in turn affects density and collisionality, which then feeds back on turbulence and overall confinement. Because this intertwined problem sits at the cutting edge of ST performance optimization, the solicitation emphasizes coordinated experiments and analyses designed to disentangle these relationships and determine what operational regimes and boundary conditions best support strong confinement in ST plasmas.

The opportunity is explicitly framed around leveraging complementary facilities, particularly the UKs MAST Upgrade (MAST-U) and the US Lithium Tokamak eXperiment Upgrade (LTX-), with context also tied to observations from NSTX-U. The idea is that MAST-U and LTX- provide different, highly relevant tools for controlling plasma density and plasma boundary conditions at low aspect ratio, allowing researchers to probe similar physics questions through distinct operational approaches. Late in the anticipated three-year research window (referenced as FY 2018 through FY 2020), MAST-U is expected to apply strong cryopumping in its advanced, highly capable divertor system to actively manage plasma density and thereby tune collisionality. In contrast, LTX- is described as relying on lithium wall coatings, combined with neutral beam heating and fueling, to reduce the return flux of cold neutrals recycled from plasma-facing surfaces. By suppressing recycling, lithium conditioning can alter edge fueling and density evolution in a fundamentally different way than cryopumping, offering a valuable comparison for isolating the drivers of improved confinement and stable operation in STs.

Beyond core plasma performance, the FOA underscores power exhaust and plasma-material interaction (PMI) as a major priority, particularly using MAST-U. Due to its compact geometry and the expectation of increased auxiliary heating power, MAST-U is projected to produce exhaust power loads to plasma-facing components that can exceed those anticipated in ITER. That combination of high heat flux relevance and MAST-Us unusually flexible divertor geometry positions the facility as a leading platform for studying how divertor configuration, boundary control, and material response interact under reactor-relevant exhaust conditions. In practical terms, this means the program is not only about achieving better confinement, but also about understanding whether those improved operating regimes can be made compatible with manageable heat and particle exhaust, acceptable material erosion and deposition behavior, and robust divertor solutions.

Administratively, the FOA is issued by the Department of Energy, Office of Science, under the research and development activity category (Science and Technology and other Research and Development) with CFDA number 81.049. The funding instrument is a grant, with eligibility listed as unrestricted (open to any type of entity, subject to any clarifications in the official eligibility text). The opportunity was created on July 5, 2017, with an original application closing date of September 1, 2017. DOE anticipated making around 10 awards, with an award ceiling of up to $3,000,000 per award, indicating support for multi-institutional or otherwise substantial research efforts consistent with the collaborative and facility-centered nature of the program.

Overall, this funding opportunity aims to accelerate progress toward two linked goals for spherical tokamaks: establishing whether low-collisionality confinement improvements are robust and explainable in terms of underlying transport and boundary physics, and demonstrating that such performance can coexist with realistic solutions for density control, wall conditioning, and especially power exhaust. By promoting coordinated work across complementary international and domestic ST facilities, the FOA is designed to produce results that are both scientifically clarifying and directly relevant to the viability of compact ST-based fusion reactor pathways.

• 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 on International and Domestic Spherical Tokamaks" 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 Jul 05, 2017.
• Applicants must submit their applications by Sep 01, 2017. (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 $3,000,000.00 in funding.
• The number of recipients for this funding is limited to 10 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.

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