Collisions of electrons with ions govern the dynamics and the radiative properties of plasmas whether they are of natural or laboratory origin. Knowledge about collision rate coefficients is essential for the modeling and understanding of any kind of plasma. During recent years heavy ion storage rings have proven to be outstanding tools for detailed measurements of cross sections and rates for electron impact ionization and recombination of ions in any given charge state ranging from H − up to U 92+. Thus, storage ring experiments with colliding electron and ion beams provide unique new access to atomic data, which are needed for plasma applications. As an example, rate coefficients for ionization and recombination of Fe 15+ ions are determined and compared with previously recommended data.