Electric Space propulsion systems, which accelerate ions or plasmas to very high exhaust velocities, are becoming more common. The DLR Institute of Aerodynamics and Flow Technology in Göttingen is testing the thrust and fuel efficiency of these systems in its large-scale Electric Space Propulsion Test Facility. The core of this system is a vacuum chamber with a length of over 12 metres and a diameter of five metres. This makes the facility one of the largest of its kind in Europe.