Some modelling and numerical aspects for instability mitigation in the tokamak ITER

Abstract: In this series of lectures, we will give a global view of the scientific aspects associated with the international tokamak named ITER , in construction in the south of France (Cadarache). After that, we will focus on the plasma confinement aspect and some of the technological and scientific challenges that will have to be addressed. Indeed, the most promising confinement mode (H-mode) is also source of multiple instabilities of the Tokamak  plasma. In some configurations, these can lead to plasma ejection and/or electron beam emissions that represent potential danger to the integrity of the machine. Disruption is one of these instabilities and leads to a displacement of the plasma that must be neutralized. Several neutralization systems will be active on ITER. Among these, cold mass injection (impurities) that aims to reduce unwanted thermal and magnetic effects on the plasma-facing components, as well as eventual forces  on the entire device. The framework being fixed, we will present in more detail the context specific to disruptions, and in particular the strategies of injection of cold matter into the plasma. We will discuss the numerical modelling assuming that plasmas can be considered as a fluid with several components. Difficulties associated with physical modelling and numerical approximation will be addressed. Some implementation strategies will be proposed in a step-by-step approach.

Second lecture will be on 3 September..