Including collisions in gyrokinetic tokamak and stellarator simulations Particle and heat transport in fusion devices often exceed the neoclassical prediction. This anomalous transport is thought to be produced by turbulence caused by microinstabilities such as ion and electron temperature gradient (ITG ETG) and trapped electron mode (TEM) instabilities the latter ones known for being strongly influenced by collisions. Additionally in stellarators the neoclassical transport can be important in the core and therefore investigation of the effects of collisions is an important field of study. Prior to this thesis however no gyrokinetic simulations retaining collisions had been performed in stellarator geometry. In this work collisional effects were added to EUTERPE a previously collisionless gyrokinetic code which utilizes the  f method. To simulate the collisions a pitch angle scattering operator was employed and its implementation was carried out following the methods proposed in [Takizuka & Abe 1977 Vernay Masters thesis 2008]. To test this implementation the evolution of the distribution function in a homogeneous plasma was first simulated where Legendre polynomials constitute eigenfunctions of the collision operator. Also the solution of the Spitzer problem was reproduced for a cylinder and a tokamak. Both these tests showed that collisions were correctly implemented and that the code is suited for more complex simulations. As a next step the code was used to calculate the neoclassical radial particle flux by neglecting ... Plasmaphysik Fusionsplasma Transporttheorie Heißes Plasma Plasmainstabilität Turbulenz Monte Carlo Simulation gyrokinetisch stellarator microinstabilitäten plasma neoklassisch