Runaway electron (RE) loads onto material structures are a major concern for future large tokamaks due to the efficient avalanching at high plasma currents. Here, we perform predictive numerical studies using the JOREK code for a plausible plasma configuration in the European DEMO fusion power plant, focusing in this paper on the scenario where the highest multi-ampere RE beam is formed. The work first comprises axisymmetric predictions of RE beam formation in a mitigated scenario and of the simultaneous vertical motion of the beam due to loss of position control. The subsequent RE beam termination triggered by a burst of magnetohydrodynamic (MHD) activity during the course of the vertical motion is then simulated in 3D with the RE fluid self-consistently coupled to the MHD modes. Finally, the resulting deposition pattern of the REs onto wall structures is calculated with a relativistic test particle approach. This way, the suitability of a possible sacrificial limiter concept for the protection of first wall components is assessed.
This paper investigates the formation, vertical motion, termination, and wall loads of runaway electron (RE) beams in the European DEMO fusion power plant. The researchers use the JOREK code to simulate these phenomena, focusing on the scenario with the highest multi-ampere RE beam. The study covers the prediction of RE beam formation, its vertical motion due to loss of position control, the subsequent termination triggered by magnetohydrodynamic (MHD) activity, and the resulting deposition pattern on the wall structures. This information is crucial for assessing the suitability of a sacrificial limiter concept to protect the first wall components.