Cluster observations of kinetic structures and electron acceleration within a dynamic plasma bubble

摘要: Fast plasma flows are believed to play important roles in transporting mass, momentum, and energy the magnetotail during active periods, such as magnetospheric substorms. In this paper, we present Cluster observations of a plasma-depleted flux tube, i.e., bubble associated with fast flow before onset substorm near-Earth tail around X = -18 R-E. The is bounded by both sharp leading (partial derivative b(z)/partial x 0) edges. two edges thin current layers (approximately ion inertial length) that carry not only intense perpendicular but also field-aligned current. edge dipolarization front (DF) within slow flow, while trailing embedded super-Alfvenic convective jet. electron jet speed exceeds thus producing large tangential at edge. drift primarily given E B drift. Interestingly, moves faster than edge, which causes shrinking local pileup inside bubble. This resulted further intensification B-z, or secondary dipolarization. Both discontinuities confine electrons Strong acceleration occurred corresponding dipolarization, fluxes dominating fluxes. We suggest betatron responsible for energization. Whistler waves lower hybrid were identified Their generation mechanisms potential dynamics discussed. Citation: Zhou, M., X. Deng, M. Ashour-Abdalla, R. Walker, Y. Pang, C. Tang, S. Huang, El-Alaoui, Z. Yuan H. Li (2013), kinetic structures dynamic bubble, J. Geophys. Res. Space Physics, 118, 674-684, doi:10.1029/2012JA018323.