Concept for a compact tokamak designS. Himmelstein | April 02, 2021
A new design is proposed for a compact fusion reactor that can generate electricity and help define the technology necessary for commercial fusion power.
General Atomics, which operates the DIII-D National Fusion Facility in San Diego, California, for the U.S. Department of Energy, developed the design in collaboration with U.S. Oak Ridge National Laboratory and U.S. Lawrence Livermore National Laboratory. The Compact Advanced Tokamak (CAT) technology is said to enable a higher-performance, self-sustaining configuration that holds energy more efficiently than in typical pulsed configurations, allowing it to be built at a reduced scale and cost.
The design evolved from first-of-a-kind reactor simulations that leverage the latest physics understanding of the current-carrying gases known as plasmas to raise performance. Increasing the pressure inside the tokamak can lead to current reductions which in turn make the plasma easier to sustain and more stable. Simulations show that by carefully shaping the plasma and moving the current toward its edge, turbulent heat losses can be suppressed to support higher pressures at lower currents and reach a state where the plasma sustains itself. CAT drives most of its own current during operation, reducing the need for expensive current-drive systems that consume generated power and reduce the plant’s efficiency.
The increased performance and energy containment of the CAT approach outlined in the journal Nuclear Fusion enables it to operate at lower plasma current than pulsed concepts. This, and continuous steady-state operation, reduce stress on the device and lower risks to machine integrity, making for a more robust, compact design with lower heat loads.