Plasma in the Polar Cusp and Plasma Mantle

Abstract

Plasma observations on HEOS 2 have shown that the plasma in the distant polar cusp generally extends far into the geomagnetic tail where it forms a layer inside the magnetopause which has been designated the plasma mantle (Rosenbauer et al., 1975). This fact is schematically illustrated in Figure 1. The extension of the plasma mantle towards lower latitudes near the dawn and dusk meridians has been detected earlier by the VELA plasma experiments and reported by Hones et al. (1972) and Akasofu et al. (1973), who used the term ‘boundary layer’. The tail lobe plasma, recently observed in the magnetotail at the orbit of the moon (Hardy et al., 1975) presumably refers to the same plasma layer.