An HTS Axisymmetric Magnetic Mirror on a Faster Path to Lower Cost Fusion Energy

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Madison, Wisconsin
Project Term:
10/01/2020 - 09/30/2024

Technology Description:

The Wisconsin High-field Axisymmetric Mirror (WHAM) project at the University of Wisconsin-Madison will leverage advances in the stability and confinement of the mirror fusion concept, innovative plasma heating, and high-field superconducting magnets to demonstrate a potentially transformative development path toward a low-cost linear fusion device. Two mirror coils will be constructed using high temperature superconducting material. Hot and high-density target plasmas will be created using high‑frequency electron-cyclotron heating from modern gyrotrons. Fast, sloshing ions will be created and energized by a novel radio-frequency heating scenario in which neutral beam injection is used to fuel ions, which are then accelerated in situ to high energy by high harmonic fast waves. The project aims to demonstrate a novel “end cell” that confines stable, heated plasmas at the end of 24 months. If successful, the plan is to demonstrate electron temperatures exceeding 1 keV and a fusion triple product in the end cell exceeding 1018 keV s/m3 at the end of 42 months. Success in this project could justify pursuit of the low-cost Break-Even Axisymmetric Tandem (BEAT) device, which would use two of the end cells at the two ends of a longer central mirror cell to pursue breakeven conditions.

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:
Prof. Cary Forest
Press and General Inquiries Email:
Project Contact Email:


Commonwealth Fusion Systems LLC
Massachusetts Institute of Technology
CompX Corporation

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