Executive Summary : | The presence of an impurity in magnetic confinement devices is inevitable due to externally launched impurities or self-generated due to sputtering from the material wall. These impurities may affect the performance of the reactor due to radiation losses and fuel dilution. However, its concentration and atomic number play a crucial role in this. If the concentration is too low, it may not affect the transport; however, if it is too high, it may cause even plasma disruption. Therefore, it is crucial to understand the impact of these impurities on plasma transport. Recent experimental observation in stellarator and tokamak demonstrates that the presence of impurities launched externally suppresses the plasma turbulence caused by ion temperature and trapped electron mode and improves the plasma confinement. Secondly, it also suppresses the localized edge modes. Gyrokinetic simulation has been rigorously used to undersatnd the turbulent transport in tokamak plasmas for the last two decades. However, very few studies have been conducted on stellarator and impurity transport. In this proposed project, we will carry out the self-consistent global simulation of turbulence transport in the presence of impurities in stellarator and tokamak. These studies will help us understand the rich physics behind the suppression of this transport. |