Exos-D Observations of Charged Particle Precipitation and Acceleration Processes

  1. Joseph R. Kan,
  2. Thomas A. Potemra,
  3. Susumu Kokubun and
  4. Takesi Iijima
  1. T. Mukai1,
  2. N. Kaya2 and
  3. W. Miyake3

Published Online: 19 MAR 2013

DOI: 10.1029/GM064p0277

Magnetospheric Substorms

Magnetospheric Substorms

How to Cite

Mukai, T., Kaya, N. and Miyake, W. (1991) Exos-D Observations of Charged Particle Precipitation and Acceleration Processes, in Magnetospheric Substorms (eds J. R. Kan, T. A. Potemra, S. Kokubun and T. Iijima), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM064p0277

Author Information

  1. 1

    The Institute of Space and Astronautical Science, Sagamihara 229, JAPAN

  2. 2

    Faculty of Engineering, Kobe University, Kobe 657, JAPAN

  3. 3

    Communications Research Laboratory, Koganei 184, JAPAN

Publication History

  1. Published Online: 19 MAR 2013
  2. Published Print: 1 JAN 1991

ISBN Information

Print ISBN: 9780875900308

Online ISBN: 9781118663981



  • Magnetospheric substorms—Congresses


The LEP (low energy particle) instrument on-board EXOS-D makes comprehensive measurements of energy and pitch-angle distributions of electrons and ions along with mass per charge analysis of positive ions. In this paper we discuss three topics on particle distributions in the polar region. (1) The clear energy dispersion of ions observed in the polar cusp can be interpreted in terms of the modified velocity filter effect in spite of complexities in the electric field. (2) With regard to the upflowing ion conics, altitude variations of the cone angle and the temperature demonstrate that the perpendicular ion energization often takes place over a wide altitude range. (3) The existence of the parallel electric field simultaneously below and above the spacecraft is often suggested by observations of ions and electrons. In order to explain the difference in the energy dependencies of upflowing ion beams by the species, we propose a new acceleration model, in which the region of the parallel electric field is confined in a narrow region, which moves upward and/or downward and whose potential drop is smaller at lower altitudes.