Retrospective of the ARPA-E BETHE-GAMOW-Era Fusion Programs and Project Cohorts

This paper provides a retrospective of the BETHE (Breakthroughs Enabling THermonuclear-fusion Energy) and GAMOW (Galvanizing Advances in Market-aligned fusion for an Overabundance of Watts) fusion programs of the Advanced Research Projects Agency-Energy (ARPA-E), as well as fusion project cohorts (associated with OPEN 2018, OPEN 2021, and Exploratory Topics) initiated during the same time period (2018-2022). BETHE (announced in 2019) aimed to increase the number of higher-maturity, lower-cost fusion approaches. GAMOW (announced in 2020) aimed to expand and translate research-and-development efforts in materials, fuel-cycle, and enabling technologies needed for commercial fusion energy. Both programs had a vision of enabling timely commercial fusion energy while laying the foundation for greater public-private collaborations to accelerate fusion-energy development. Finally, this paper describes ARPA-E's fusion Technology-to-Market (T2M) activities during this era, which included supporting ARPA-E fusion performers' commercialization pathways, improving fusion costing models, exploring cost targets for potential early markets for fusion energy, engaging with the broader fusion ecosystem (especially investors and nongovernmental organizations), and highlighting the importance of social license for timely fusion commercialization.