Impact of various plasma instabilities on reliability and performance of tokamak fusion devices

Abstract

Plasma instability events such as disruptions, resulting runaway electrons, edge-localized modes (ELM), and vertical displacement events (VDE) are mainly the most limiting factor for successful tokamak reactor concept. The plasma-facing components (PFC), e.g., wall, divertor, and limited surfaces of a tokamak as well as coolant structure materials are subjected to intense particle and heat loads and must maintain a clean and stable surface environment between them and the core/edge plasma. This is critical to fusion device performance. Comprehensive research efforts are developed utilizing the HEIGHTS simulation package to study self-consistently various effects of high power transient on material operation/selection. The package consists of several models that integrate different stages of plasma–wall interactions starting from energy release at scrape-off-layer and up to the transport of the eroded debris and splashed wall materials as a result of the deposited energy. The integrated model predicts material loss, PFC lifetime from transients, and effects on core plasma performance. HEIGHTS initial simulation shows that a single event such as a major disruption, VDE, or runaway electron could severely damage the reactor wall and structural materials and disrupt operation for a significant time. HEIGHTS is used to identify safer operating window regimes and upper transient limits that PFC can withstand during various instabilities.