Comparing and contrasting dispersionless injections at geosynchronous orbit during a substorm event

Kronberg, E. A.; Grigorenko, E. E.; Turner, D. L.; Daly, P. W.; Khotyaintsev, Y. und Kozak, L. (2017): Comparing and contrasting dispersionless injections at geosynchronous orbit during a substorm event. In: Journal of Geophysical Research-Space Physics, Bd. 122, Nr. 3: S. 3055-3072

Abstract

Particle injections in the magnetosphere transport electrons and ions from the magnetotail to the radiation belts. Here we consider generation mechanisms of dispersionless injections, namely, those with simultaneous increase of the particle flux over a wide energy range. In this study we take advantage of multisatellite observations which simultaneously monitor Earth's magnetospheric dynamics from the tail toward the radiation belts during a substorm event. Dispersionless injections are associated with instabilities in the plasma sheet during the growth phase of the substorm, with a dipolarization front at the onset and with magnetic flux pileup during the expansion phase. They show different spatial spread and propagation characteristics. Injection associated with the dipolarization front is the most penetrating. At geosynchronous orbit (6.6R(E)), the electron distributions do not have a classic power law fit but instead a bump on tail centered on similar to 120keV during dispersionless electron injections. However, electron distributions of injections associated with magnetic flux pileup in the magnetotail (13R(E)) do not show such a signature. We surmise that an additional resonant acceleration occurs in between these locations. We relate the acceleration mechanism to the electron drift resonance with ultralow frequency waves localized in the inner magnetosphere.

• Dokumententyp: Zeitschriftenartikel
• Fakultät: Geowissenschaften > Department für Geo- und Umweltwissenschaften
• Themengebiete: 500 Naturwissenschaften und Mathematik > 550 Geowissenschaften, Geologie
• ISSN: 2169-9380
• Sprache: Englisch