Design and construction of an energy breakeven negative triangularity tokamak

In recent years Negative Triangularity (NT) has taken the spotlight as a promising path to commercial fusion. Hephaestus has been designing and constructing an NT reactor targeting energy breakeven. NT reactors can deliver high performance fusion scenarios [Paz-Soldan NF 24] at reduced costs, achieving high confinement without ELM instabilities. Our studies show NT enables a 3 times reduction in auxiliary heating needed to reach Q>1, compared to an H-mode scenario which needs to meet the L-H transition threshold. With the divertor at a larger radius in NT, the power handling challenge is also reduced. Here we present the details of a reactor in the early stages of construction, allowing testing of operational domains based on recent promising operational limits and confinement studies [Thome PPCF 24, Balestri PPCF 24].

We will operate a high magnetic field, high plasma current, short pulse, compact reactor to demonstrate the advantages of negative triangularity where Q>1 is expected with 10 MW ICRH heating. Our experimental plan also includes technology validation for commercial power plants such as blanket modules in collaboration with other research groups. Our aim is to validate into hardware the physical and economic advantages of commercially relevant NT tokamaks.