Optimization of DEMO geometry and disruption location prediction

Abstract The design study of DEMO is one of the main points of the European Roadmap to Fusion Electricity. The present pre-conceptual design phase of DEMO is used to explore a flexible range of the main machine geometrical design parameters and plasma scenarios. This paper presents the electromagnetic (EM) modelling of the DEMO baseline scenario, including the optimization activities on the electrically conductive structures surrounding the plasma and their influence on the passive vertical stabilization (VS). The improvements on the passive and active VS allowed increasing the maximum controllable plasma elongation, with a consequent increase on the fusion performance. Finally, a study is presented on the possibility to predict the plasma final position following a vertical displacement event (VDE). This prediction capability supports the development of a wall protection strategy from plasma transients. A model is presented based on the assumptions on the characteristic time constants expected for the current quench (CQ) time and L/R time constant of the conductive structures.