The ion optics in the ion-source chamber of a magnetic sector mass spectrometer extract and accelerate ions. The ions enter the flight tube between the poles of a magnet and are deflected by the magnetic field. Only ions of a mass-to-charge ratio that have equal centrifugal and centripetal forces pass through the flight tube. Other ions collide against the magnet wall and will not be detected. By varying the acceleration voltage or the magnetic field strength, a complete spectrum (an m/z range of e.g. 50 to 2000) can be obtained.