Demonstration of Low-Density, High-Performance Operation of Sustained Spheromaks and Favorable Scalability toward Compact, Low-Cost Fusion Power Plants

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Seattle, Washington
Project Term:
07/01/2020 - 06/30/2023

Critical Need:

Controlled fusion has long been thought of as an ideal energy source—safe, clean, abundant, and dispatchable. Fusion is on the cusp of demonstrating net positive energy gain, spurring interest in both the public and private sectors to adopt a more aggressive development path toward a timely, grid-ready demonstration. A critical need today is to increase the performance levels and the number of lower-cost fusion approaches that might eventually lead to commercial fusion energy with competitive capital cost and levelized cost of energy. To address this need, the BETHE program supports (1) advancing the performance of earlier-stage, lower-cost concepts, (2) component-technology development to lower the cost of more-mature concepts, and (3) capability teams to assist multiple concept teams in theory, modeling, and diagnostic measurements.

Project Innovation + Advantages:

The University of Washington will advance the technical viability of a novel method, Imposed-Dynamo Current Drive (IDCD), for sustaining and heating spheromak plasmas as the basis of compact, low-cost fusion power plants. A traditional tokamak fusion reactor has a toroidal confinement area, similar shape to a donut, with a hole in the middle. The spheromak reduces the size of the hole as much as possible, resulting in a spherical plasma shape similar to a cored apple. IDCD can efficiently couple large amounts of power to the plasma at much lower costs relative to other methods of higher-frequency plasma heating. The proposed R&D aims to achieve spheromak ion and electron temperatures > 100 eV during sustainment on an existing experimental prototype. Other R&D activities include computational tasks to support both the scientific and engineering design of next-step prototypes with higher fusion performance. This project will increase the technological readiness level of this lower-cost fusion concept to encourage further development toward commercial fusion energy with both public and private support.

Potential Impact:

Accelerating and lowering the costs of fusion development and eventual deployment will enable fusion energy to contribute to:


Fusion energy will ensure the U.S.’s technological lead and energy security.


Fusion energy will improve our chances of meeting growing global clean-energy demand and realizing cost-effective, net-zero carbon emissions, while minimizing pollution and avoiding long-lived radioactive waste.


As a disruptive technology, fusion energy will likely create new markets, opportunities, and export advantages for the U.S.


ARPA-E Program Director:
Dr. Ahmed Diallo
Project Contact:
Dr. Christopher Hansen
Press and General Inquiries Email:
Project Contact Email:

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