Surveys on magnetospheric plasmas based by the Double Star Project (DSP) exploration
Publication date: 15 Oct 2008
Authors: Shen, C. et al.
Journal: Science in China Series E: Technological Sciences
Copyright: Science in China Press, SpringerThe equatorial and polar satellites of the Double Star Project (DSP) were launched successfully on December 29, 2003 and July 25, 2004, respectively, and both of them are operating smoothly. The DSP provides a good opportunity for investigating the structure of the magnetosphere. Based on the DSP data collected during 2004, we have surveyed the distribution of the magnetic fields and plasmas in the magnetosphere. It is found that: (1) Near the Earth's equatorial plane within geocentric distances of less than 7 RE, the Earth's magnetic field is dipolar. In the vicinity of the magnetopause, the magnetic field is enhanced by a factor of about 1.5, and on the nightside, the magnetic field can vary significantly from the Earth's dipole field, likely caused by the presence of the near-Earth tail current sheet. (2) In the day-side magnetosheath, the electron and ion densities are usually both in the range of 10-30 cm-3; the ion and electron temperatures are usually about 200 and 50 eV, respectively. The flow pattern is usually smooth, with a low velocity in the subsolar region and with significantly higher velocities in the dawn and dusk flanks. (3) In the region between the magnetopause and plasmasphere the density is low, approximately 0.5-5 cm-3, and the temperature is high, about 1-10 keV for ions and 0.1-5 keV for electrons. The ion temperature has an apparent anisotropy, with the ratio of the perpendicular and parallel temperatures being about 1.0-1.3 for the night-and dusk-side magnetosphere and about 1.3-2.0 for the day-and dawn-side magnetosphere. -- Remainder of abstract is truncated --