Disruption modelling for engineering and physics design of Tokamak Energy’s Spherical Tokamak Fusion Pilot Plant

Plasma disruptions pose significant risks to high-performance plasma operations, threatening both machine integrity and operational availability. Consequently, the design of future fusion devices aims to minimise the causes of such events as much as possible. Therefore, evaluating and characterising the effects of plasma disruptions is crucial in the design of a future fusion energy reactor. To support the conceptual design phase of a Spherical Tokamak Fusion Pilot Plant (ST-FPP) project, developed by Tokamak Energy, this paper presents a disruption modelling approach applied to different conceptual design stages of the machine.

The approach takes into account the various physics and engineering aspects involved at each stage. From an engineering perspective, disruption modelling was conducted on several ST-FPP design layout options with the aim of exploring the Electro-Magnetic (EM) response of the structures, in order to compare and contrast the different design solutions. Regarding the physics point of view, a range of disruption scenarios were numerically modelled, focusing on key plasma parameters across the target operational space, plasma material interaction and correlated thermal loads effects. Additionally, potential discrepancies arising from disruptions originating from different reference equilibria were examined, with an initial focus on Double Null Diverted (DND) and Single Null (SN) configurations. This analysis highlights the contrasting plasma disruption behaviours and their corresponding effects on the structural components.

These disruption studies have proven to be a key driver in a ST-FPP design investigations from both engineering and physical perspectives, aiming to provide valuable understanding for the design of future fusion devices.