Abstract: Methods and systems for analyzing ions in a magnetic ion trap are provided herein. In accordance with various aspects of the present teachings, the methods and systems described herein enable Fourier transform ion cyclotron resonance mass spectrometry across relatively narrow gap magnetic fields substantially perpendicular to the axis along which the ions are injected into the ion trap. As a result, smaller, less expensive magnets can be used to produce the high-intensity, uniform magnetic fields utilized in high performance FT-ICR/MS applications. Accordingly, the present teachings enable permanent magnets (as well as electromagnets) to generate these magnetic fields, potentially reducing the cost, size, and/or complexity of the systems described herein relative to conventional FT-ICR systems.