Dipolarizing flux bundles in the cis-geosynchronous magnetosphere: relationship between electric fields and energetic particle injections

Thursday, 17 December 2015
Poster Hall (Moscone South)
Jiang Liu1, Vassilis Angelopoulos2, Xiao-Jia Zhang2, Drew L Turner3, Christine Gabrielse1, Andrei Runov1, Herbert O Funsten4 and Harlan E. Spence5, (1)University of California Los Angeles, Los Angeles, CA, United States, (2)University of California Los Angeles, Earth, Planetary, and Space Sciences, Los Angeles, CA, United States, (3)Aerospace Corporation El Segundo, El Segundo, CA, United States, (4)Los Alamos Natl Laboratory, Los Alamos, NM, United States, (5)University of New Hampshire Main Campus, Space Science Center, Durham, NH, United States
Dipolarizing flux bundles (DFBs) are small flux tubes (typically < 3 RE in XGSM and YGSM) in the nightside magnetosphere that have magnetic field more dipolar than the background field. Although DFBs are known to accelerate particles to create energetic particle injections, their acceleration mechanism and importance in generating injections inside geosynchronous orbit remain open questions. To answer these questions, we investigate DFBs in the inner magnetosphere by conducting a statistical study with data from the Van Allen Probes. The results show that just like DFBs outside geosynchronous orbit, those inside that orbit occur most often in the pre-midnight sector. Half the DFBs are accompanied by energetic particle injection. Statistically, DFBs with injection have an electric field three times that of those without. All the injections accompanying DFBs appear dispersionless within the temporal and energy resolution considered. These findings suggest that the injections are ushered or locally produced by the DFB, and the DFB’s strong electric field is an important aspect of the injection generation mechanism.