Effect of impurities on kinetic transport processes in fusion plasmas Impurity ions pose a potentially serious threat to fusion plasma performance by affecting the confinement in various usually deleterious ways. Due to the creation of helium ash during fusion reactions and the interaction of the plasma with the wall components which makes it possible for heavy ions to penetrate into the core plasma impurities can intrinsically not be avoided. Therefore it is essential to study their behaviour in the fusion plasma in detail. Within the framework of this thesis different problems arising in connection with impurities have been investigated. 1. Collisional damping of zonal flows in tokamkas: The effect of impurities on the collisional damping of zonal flows is investigated. Since the Coulomb collision frequency increases with increasing ion charge heavy highly charged impurities play an important role in this process. The effect of such impurities on the linear response of the plasma to an external potential perturbation as caused by zonal flows is calculated with analytical methods and compared with numerical simulations resulting in good agreement. 2. Impurity transport driven by microturbulence in tokamaks: Fine scale turbulence driven by microinstabilities is a source of particle and heat transport in a fusion reactor. A semi analytical model is presented describing the resulting impurity fluxes and the stability boundary of the underlying mode ... Plasmaphysik Fusionsplasma Kinetische Transporttheorie Verunreinigungstransport Fusion plasmas Kinetic Transport Theory Impurities