Storm-time evolution of energetic electron pitch angle distributions by wave-particle interaction

摘要

The quasi-pure pitch-angle scattering of energetic electrons driven by eld-aligned propagating whistler mode waves during the 9 similar to 15 October 1990 magnetic storm at L approximate to 3 similar to 4 is studied, and numerical calculations for energetic electrons in gyroresonance with a band of frequency of whistler mode waves distributed over a standard Gaussian spectrum is performed. It is found that the whistler mode waves can efficiently drive energetic electrons from the larger pitch-angles into the loss cone, and lead to a flat-top distribution during the main phase of geomagnetic storms. This result perhaps presents a feasible interpretation for observation of time evolution of the quasi-isotropic pitch-angle distribution by Combined Release and Radiation Effects Satellite (CRRES) spacecraft at L approximate to 3 similar to 4.