Structure and properties of the Earth's plasmasphere. Experimental data and problems of their interpretation (review)

Abstract

The results of direct measurements of the concentration and temperature of the plasma are discussed, together with the mass and charge makeup of the plasmasphere ions. For the most part, the data were obtained during the last decade. It is shown that the data confirm the existence of two zones in the plasmasphere: an inner zone, which is stable, quasi-stationary, and cold; and an outer zone, which is usually warm and essentially nonstationary, with large longitudinal gradients of the parameters. The limit of the outer zone, the plasmapause, is clearly expressed during the evening-nighttime hours and is usually washed out in the day sector. It has a complex and nonstationary structure, changes strongly as a function of geomagnetic conditions, and is asymmetric in local time, with the evening and midday projections of the plasmapause being reliably distinguished. A comparison of these data with the theoretical constants leads to the conclusion that at present there is no generally accepted model that adequately describes all the basic features of the observed structure and dynamics of the plasmapause.