The discovery of long-lived electrostatic coherent structures with large-amplitude electric fields (1 ≤ E ≤ 500 mV/m) by the Van Allen Probes has revealed alternative routes through which planetary radiation belts' acceleration can take place. Following previous reports showing that small phase-space holes, with q φ/Tc e ≃ 10-2 10-3, could result from electron interaction with large-amplitude whistlers, we demonstrate one possible mechanism through which holes can grow nonlinearly (i.e., γ ∝ √ φ) and subcritically as a result of momentum exchange between hot and cold electron populations. Our results provide an explanation for the common occurrence and fast growth of large-amplitude electron phase-space holes in the Earths radiation belts.
- acceleration of particles
- planetary systems