Ion Optics for Mass Spectrometers with Normal Focal Planes

The expressions for the focal plane geometry and the angle included be-tween the focal plane and the optical axis of a mass spectrometer are derived.The methods to correct second order chromatic aberration coefficient (x/θδ)and obtain a normal focal plane are discussed, they are adding a sextupole,machining a concave boundary at the exit of the sector magnet and shimmingthe magnetic field of the dipole magnet to have sextupole component. Someprojects of mass spectrometers with normal focal planes and second order an-gular aberration corrections are given.