Pulsed High Temperature Superconducting Central Solenoid For Revolutionizing Tokamaks

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Cambridge, Massachusetts
Project Term:
10/01/2020 - 03/31/2023

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 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 tokamak is the most scientifically mature fusion energy concept, which confines hot plasma in the shape of a torus (similar to a donut). This plasma is controlled in part by a central solenoid electromagnet. Using high-temperature superconductors (HTS) and an innovative design, Commonwealth Fusion Systems (CFS) and its partners aim to build a central solenoid capable of quickly changing (“fast ramping”) its current and magnetic field, while also being robust enough to survive many thousands of cycles. This new HTS magnet will enable a new mode of tokamak operation, in which power output is repetitively pulsed. By comparison, traditional, steady-state tokamaks require expensive and complex external current-drive systems, and aggressive plasma physics with substantial scientific risk. The pulsed-tokamak power-plant pathway has the potential to reduce costs, speed timelines, and revolutionize the future of fusion power.

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. Robert Mumgaard
Press and General Inquiries Email:
Project Contact Email:


Lawrence Berkeley National Laboratory
Brookhaven National Laboratory
Massachusetts Institute of Technology

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