The content from this description has been adapted from the CAPSinstrument description paper [YOUNGETAL2004].
The CAPS instrument was comprised of three sensors: the Electron Spectrometer (ELS), the Ion Beam Spectrometer (IBS), and the Ion Mass Spectrometer (IMS). The ELS sensor measured the velocity distribution of electrons from 0.7 eV to 30 keV, a range that permited coverage of thermal electrons found at Titan and near the ring plane as well as more energetic trapped electrons and auroral particles. The IBS sensor measured ion velocity distributions with very high angular and energy resolution from 1 eV to 50 keV. It was specially designed to measure sharply defined ion beams expected in the solar wind at 9.5 AU, highly directional rammed ion fluxes encountered in Titan's ionosphere, and anticipated field-aligned auroral fluxes. The IMS sensor was designed to measure the composition of hot, diffuse magnetospheric plasmas and low-concentration ion species with an atomic resolution M/delta M ~70 and, for certain molecules, (such as N2+ and CO+), effective resolution as high as ~2500. The three sensors were mounted on a motor-driven actuator that rotates the entireinstrument over approximately one-half of the sky every 3 minutes.