Low‐energy electrons (5–50 keV) in the inner magnetosphere

Abstract

[1] Transport and acceleration of the 5-50 keV electrons from the plasma sheet to geostationary orbit were investigated. These electrons constitute the low-energy part of the seed population for the high-energy MeV particles in the radiation belts and are responsible for surface charging. We modeled one nonstorm event on 24-30 November 2011, when the presence of isolated substorms was seen in the AE index. We used the Inner Magnetosphere Particle Transport and Acceleration Model (IMPTAM) with the boundary at 10 R E with moment values for the electrons in the plasma sheet. The output of the IMPTAM modeling was compared to the observed electron fluxes in 10 energy channels (from 5 to 50 keV) measured on board the AMC 12 geostationary spacecraft by the Compact Environmental Anomaly Sensor II with electrostatic analyzer instrument. The behavior of the fluxes depends on the electron energy. The IMPTAM model, driven by the observed parameters such as Interplanetary Magnetic Field (IMF) B y and B z , solar wind velocity, number density, dynamic pressure, and the Dst index, was not able to reproduce the observed peaks in the electron fluxes when no significant variations are present in those parameters. We launched several substorm-associated electromagnetic pulses at the substorm onsets during the modeled period. The observed increases in the fluxes can be captured by IMPTAM when substorm-associated electromagnetic fields are taken into account. Modifications of the pulse front velocity and arrival time are needed to exactly match the observed enhancements.

Acceleration of ions by electric field pulses in the inner magnetosphere

“…These very rough estimates show that the proposed acceleration mechanism is worth studying for relativistic electrons. This mechanism could supplement traditional electron acceleration during injections [ Li et al , , ; Sarris and Li , ; Gabrielse et al , ; Ganushkina et al , ; Gabrielse et al , ; Ganushkina et al , ].…”

Space Weather Effects Produced by the Ring Current Particles

“…There have been several studies aimed at the modeling of electron injections as they are well-known signatures of a substorm in the near-Earth space (Li et al 1998;Zaharia et al 2000;Sarris et al 2002;Gabrielse et al 2012Gabrielse et al , 2014Gabrielse et al , 2016Ganushkina et al 2013Ganushkina et al , 2014. These models give relatively good agreement with the observed dispersionless electron injections at geostationary orbit during specific events (Ingraham et al 2001;Fok et al 2001a;Li et al 2003;Mithaiwala and Horton 2005;Liu et al 2009).…”

“…This model also provides the equatorial electron fluxes as functions of time, energy and pitch angle but it is not run in real time with no comparison with the observations. The model which runs online in real time and which outputs are directly compared to the real time observations for low energy (< 200 keV) electrons is Inner Magnetosphere Particle Transport and Acceleration model (IMPTAM) (Ganushkina et al 2013(Ganushkina et al , 2014(Ganushkina et al , 2015a. IMP-TAM operates online (imptam.fmi.fi) under the completed FP7 SPACECAST and SPACES-TORM projects (http://fp7-spacecast.eu, http://www.spacestorm.eu/) funded by the European Union Seventh Framework Programme and under the on-going H2020 PROGRESS project (https://ssg.group.shef.ac.uk/progress2/html/) funded by the European Union's Horizon 2020 research and innovation programme.…”

Drift‐Dispersed Flux Dropouts of Energetic Electrons Observed in Earth's Middle Magnetosphere by the Magnetospheric Multiscale (MMS) Mission

“…Previous studies (e.g., Angelopoulos et al, 2008;Baker et al, 1996) suggest that some energetic particle injections result from earthward moving plasma (e.g., plasma bubbles or dipolarizing flux bundles) associated with a sharp enhancement in the z component of the magnetic field (i.e., dipolarization or dipolarization front). However, the nature of the geometry of this electric field pulse in the magnetotail remains unknown as different models have yielded widely different results, spanning from highly localized in MLT (e.g., Gabrielse et al, 2016;Gabrielse et al, 2017) to encompassing much of the plasma sheet (e.g., Ganushkina et al, 2014). However, the nature of the geometry of this electric field pulse in the magnetotail remains unknown as different models have yielded widely different results, spanning from highly localized in MLT (e.g., Gabrielse et al, 2016;Gabrielse et al, 2017) to encompassing much of the plasma sheet (e.g., Ganushkina et al, 2014).…”