Princeton Plasma Physics Laboratory (PPPL)

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.

Princeton Plasma Physics Laboratory (PPPL) will design and build a prototype structure with an array of rare-earth permanent magnets to generate the precise shaping fields of an optimized, quasi-axisymmetric stellarator design. The stellarator is an attractive fusion-energy concept because it has minimal recycling power and auxiliary systems, and no-time dependent electro-magnet systems. Two challenges have delayed its progress: 1) obtaining adequate confinement in three-dimensional (3D) fields and 2) engineering the magnetic configuration with sufficient precision at low cost. Breakthroughs in calculating and optimizing confinement properties of 3D magnetic systems have addressed the first challenge. A recent concept proposes permanent magnets and simple planar coils for making the complex fields required by stellarators. Use of permanent magnets along with planar toroidal field coils could dramatically simplify stellarator construction, assembly, and maintenance, and place the stellarator on a compelling path toward lower-cost fusion energy.