This PhD thesis consists of planning, simulating, building, testing and characterizing a new electron cyclotron resonance (ECR) ion source, SWISSCASE. the Solar Wind Ion Source Simulator for the CAlibration of Space Experiments located at the University of Bern, Switzerland. The ion source will be operated in the existing CASYMS ultra high vacuum (UHV) facility and will extend the application field of the existing filament electron collision ion source inside CASYMS and the existing electron cyclotron resonance ion source MEFISTO, operated in its own UHV facility. The chosen ECR ionization concept operating at 10.88 GHz delivers high currents of highly charged ions of up to 2 µA for Ar8+ and a maximum identified charge state of Ar12+. In addition to argon, the ECR plasma of SWISSCASE has been operated with krypton, xenon and carbon dioxide gas, revealing all of the expected charge states and featuring a charge states distribution in favor of highly charged ions. Design constraints were given by the final application of SWISSCASE being implemented in CASYMS with limited space and power. The new ion source was realized with limited funding. Numerical simulations gave insight in unprecedented quality and detail about the complex three dimensional extent of the magnetic field distribution of the full permanent magnet confinement of both, SWISSCASE and MEFISTO, the second ECR ion source, operated since 1997 at the University of Bern. For both confinement systems, the isocontour surface, defined by the electron cyclotron resonance condition of the incident microwave, is visualized in 3D. In addition to the realization of the ECR ion source, a plasma Bremsstrahlung measurement revealed an average ECR electron temperature of 10 keV for an argon plasma. This temperature was used to perform numerical simulations of electron trajectories inside the SWISSCASE and the MEFISTO confinement. The simulated magnetic field distribution of MEFISTO and the simulated electron distribution of SWISSCASE are closely related to the observed triangle shaped surface coating patterns found in hexapole confined ECR ion sources.