Low-altitude electron acceleration due to multiple flow bursts in the magnetotail
Nilsson, H.; Hamrin, M.; Marghitu, O.; Karlsson, T.; Nakamura, R.; Frey, H. U.; Keiling, A.; Kubyshkina, M. V.; Amm, O.; Forsyth, C.; Vogt, J.; Bunescu, C.; Constantinescu, V.; Sorbalo, E.; Semeter, J.
Austria, Sweden, Romania, Finland, United States, Germany, United Kingdom, Russia
Abstract
At 10:00 UT on 25 February 2008, Cluster 1 spacecraft crossed the near-midnight auroral zone, at about 2 RE altitude, while two of the Time History of Events and Macroscale Interactions During Substorms (THEMIS) spacecraft, THD and THE, observed multiple flow bursts on the near-conjugate plasma sheet field lines. The flow shear pattern at THEMIS was consistent with the vortical motion at duskside of a localized flow channel. Coinciding in time with the flow bursts, Cluster 1 observed bursts of counterstreaming electrons with mostly low energies (≤441 eV), accompanied by short time scale (<5 s) magnetic field disturbances embedded in flow-associated field-aligned current systems. This conjugate event not only confirms the idea that the plasma sheet flows are the driver of the kinetic Alfvén waves accelerating the low-energy electrons but is a unique observation of disturbances in the high-altitude auroral region relevant to the multiple plasma sheet flows.