A tophat ring current sensor Original Research Article

Observational knowledge of ring current particle pitch angle distributions and the theoretical understanding of such distributions in terms of particle transport and loss mechanisms are still incomplete. The recovery phase of major storms is associated with the loss of ring current ions through charge exchange with exospheric neutrals, wave particle scattering such as the ion cyclotron waves or Pc5 waves, or through E×B convection to the front side magnetosphere. Modelers often need to postulate additional pitch angle diffusion in order to fit the observed anisotropies. We describe here a ring current sensor based on existing technologies and concepts. The proposed instrument is a tophat analyzer with a time-of-flight section. The instrument is designed to detect with high pitch angle resolution ions that form the Earthʹs ring current within the energy range of 10 to 300 keV. High pitch angle resolution allows distinguishing between different ring current decay mechanisms.