Open AccessParticle transport and energization associated with substorms
Author(s) -
Zaharia Sorin,
Cheng C. Z.,
Johnson Jay R.
Publication year - 2000
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/1999ja000407
Subject(s) - substorm , physics , electric field , computational physics , flux (metallurgy) , geophysics , magnetic field , magnetosphere , geosynchronous orbit , particle (ecology) , earth radius , atomic physics , satellite , oceanography , materials science , quantum mechanics , astronomy , metallurgy , geology
Energetic particle flux enhancement events observed by satellites during substorms are studied by considering the interaction of particles with earthward propagating electromagnetic pulses of westward electric field and consistent magnetic field of localized radial and azimuthal extent in a background magnetic field. The energetic particle flux enhancement is mainly due to the betatron acceleration process: particles are swept by the earthward propagating electric field pulses via the E × B drift toward the Earth to higher magnetic field locations and are energized because of magnetic moment conservation. The most energized particles are those which stay in the pulse for the longest time and are swept the longest radial distance toward the Earth. Assuming a constant propagating velocity of the pulse, we obtain analytical solutions of particle orbits. We closely examine substorm energetic particle injection by computing the particle flux and comparing with geosynchronous satellite observations. Our results show that for pulse parameters leading to consistency with observed flux values, the bulk of the injected particles arrive from distances of less than 9 R E , which is closer to the Earth than the values obtained by the previous model (Li et al., 1998).