Improved understanding of runaway-electron formation and decay processes are of prime interest for the safe operation of large tokamaks, and their dynamics during dynamical scenarios such as disruptions are of particular concern. In this contribution, we present kinetic modelling of scenarios with time-dependent plasma parameters – in particular, we investigate hot-tail runaway generation during a rapid drop in plasma temperature. With the goal of studying runaway-electron generation with a self-consistent electric field-evolution, we also discuss the implementation of a conservative collision operator and demonstrate its properties. An operator for avalanche runaway-electron generation which includes the proper energy dependence of the runaway distribution, is investigated, and the avalanche growth rate is shown to be significantly affected in some parameter regimes. These developments all pave the way for an improved modelling of runaway-electron dynamics during disruptions or other dynamic events.
Projektet är avslutat: 2017-12-31