Thermal O^++ Ions according to Mass-Spectrometer Data Obtained from the lnterkosmos-24 and lnterkosmos-25 Satellites. Part II. Interpretation

The basic equations are presented which, under certain assumptions, allow one to reconstruct the distribution of densities of charged particles of thermal plasma along the geomagnetic field lines from 1000 km up to the equatorial plane of the magnetosphere by analyzing the local (along the orbit) satellite data on the ion composition, density, and temperature of electrons in Earthʹs plasmasphere. On the basis of the reconstruction of ionospheric plasma characteristics from the lnterkosmos-24 satellite data, we give the interpretation of the basic regularities in variation of the concentration of O^++ ions presented in [1]. These regularities are found to be stipulated by the following factors: (1) various characteristics of variation of N(O^++) above and below the protonosphere boundary; (2) the dependence of position of this boundary on the value of plasma flux along the geomagnetic field; (3) the strong dependence of N(O^++) on the charged particlesʹ temperature gradient along the geomagnetic field. It is shown, in particular, that the existence of a maximum in the latitudinal dependence of N(0^++) inside the plasmasphere and the displacement of this maximum toward higher latitudes are caused by the latitudinal dependence of the N(0^+)/N(H^+) ratio and by an increase of the temperature gradient of charged particles with the invariant latitude. The value of this displacement was found to nonlinearly depend on the altitude. For nighttime winter conditions at the late stage of a magnetic stormʹs recovery phase, it was found that in the region of the electron temperature peak, which is associated with the ring current of the magnetosphere, the high values of N(0^+) ~10^3 cm^-1 can extend up to 2000 km. It is established on the basis of calculations that in this period near the L-shell of a peak of Te there exists a cavity in the electron concentration, which is stretched almost along the whole nonfixed L-shell: L increases as it approaches the geomagnetic equator.