Intensity-driven beam instabilities are studied in simulations with a refined impedance model and in experimental measurements for this thesis. The High Luminosity Large Hadron Collider (HL-LHC) project at CERN aims for an increase in the integrated luminosity in the Large Hadron Collider (LHC). To achieve this goal the LHC injector chain has to be upgraded. The last LHC injector, the Super Proton Synchrotron (SPS), intends to accelerate beams with twice the present intensity.