Observations of atomic oxygen (O⁺) in the Earth's magnetotail

Abstract

The electrostatic analyzer aboard Imp 7 examined energy spectra of positive ions in certain streaming plasmas adjacent to the plasma sheet and within the geomagnetic tail at geocentric radial distances of about 35 R-E, revealing minor, though often persistent, secondary maxima of intensities with energy per unit charge a factor of 16 greater than that of the maxima corresponding to the dominant H(+) ions. The secondary maximum at higher E/Q was identified as a small flux of singly ionized atomic oxygen O(+), from the ionosphere. O(+) fluxes in the geomagnetic tail were about 10 to the 5th/(sq cm s) and imply O(+) upward fluxes in the upper ionosphere of about 10 to the 8th/(sq cm s). The kinetic energy of the oxygen ions is about 1-5 keV, while estimates of the global escape of the ions are about 3 x 10 to the 6th kg/yr.