Dependence of the Luminosity on Various Machine Parameters and Their Optimization at PETRA

The luminosity of a storage ring is determined by the beam currents, by the natural beam size at the interaction points and by the increase in beam height due to the beam-beam interaction. The limitation of the currents, the variation of the beam size and the minimization of the blow-up as predicted by computer simulations are discussed. Results of the optimization of the luminosity in PETRA are shown.