Runaway electrons in fusion plasmas

Research Project, 2023 – 2026

High-current tokamaks will be susceptible to conversion of the plasma current into a highly energetic runaway electron (RE) beam during plasma initiation and termination events. Such RE beams affect the plasma dynamics and might damage plasma facing components. The goal of this project is to develop methods for avoidance and suppression of REs. This is essential to ensure the safe and reliable operation of future fusion devices. Both plasma initiation and termination are characterized by dramatic transient changes, strong parameter variations (of e.g. density, temperature) and processes operating across a wide range of spatio-temporal scales and in nonlinear regimes. Controlling such behaviour requires theoretical models that capture the inherently multiscale nature of the phenomena, as well as efficient numerical tools and optimization frameworks. We will develop such a tool-set and use it to understand and control RE dynamics during tokamak plasma initiation and termination, including the effect of shattered pellet injection and instabilities. The modelling tools will be validated against experiments using synthetic radiation diagnostic tools, and will be employed to evaluate methods for avoidance or benign termination of RE beams.