Ion measurements from Cluster‐CIS were used to characterize and interpret the signatures of PSBL energy‐dispersed ions and their fine structure. On 14 February 2001, several ion injections were encountered by SC 1 and SC 3, separated by ∼530 km, during an outbound orbit at 4.5 RE. Both satellites recorded the same ion structures. The energy dispersion of each ion structure was dominated by the time‐of‐flight effect (TDIS). In addition, we show evidence for spatial properties of the ion injections: (1) SC 1 and SC 3 encountered the same ion structures with a time delay of ∼30 s, which indicates their spatial extent. (2) The peak energy of each injection increased with increasing latitude. We propose a scenario in which both temporal and spatial effects are incorporated: Ion beamlets are impulsively and recurrently injected from separated regions distributed along the tail current sheet (ranging from X ∼70 to 110 RE) into latitudinally narrow (∼600 km to 1800 km) and convecting (at ∼10 km/s) flux tubes of the PSBL. Beamlets injected closer to the X line gain higher energies as a result of the intrinsic dispersion effect.
