  The comprehensive suite of scientific instruments with high temporal
resolution measurements on the Mars Atmosphere and Volatile Evolution (MAVEN)
spacecraft allowed studies of the structure and properties of the dayside
magnetosphere of Mars. The dayside plasma envelope was found on first Mars
orbiters (Vaisberg et al., 1976, Gringauz et al., 1976), but only the high
temporal and mass resolutions of MAVEN instruments allowed investigations of
the structure and processes of plasma of the dayside magnetosphere, the plasma
layer which exists between shocked solar wind and ionosphere (Vaisberg et al.,
2017). It was found that in the different dayside conditions the two different
plasma layers form between the magnetosheath and ionosphere: (1) the mixture of
heated ionospheric ions and energetic pick-up exospheric ions and (2) the layer
of accelerated ionospheric ions population that forms the lower energy part of
the plume formation. The first type of dayside magnetosphere of Mars is formed
by the interaction of pick-up oxygen ions of exospheric origin with the topside
of Mars' ionosphere (Vaisberg and Shuvalov, 2021). The second plasma layer
between magnetosheath flow and ionosphere forms from initial lower energy part
of the plume that is accelerated and continues in the magnetosheath. In this
paper we show typical plasma populations, their properties and conditions that
lead to formation of the dayside magnetosphere mainly from the material
provided by the upper layer of the ionosphere. As the annex we include 115
dayside magnetosphere crossings of both types that were analyzed in the paper.

Space Physics;Plasma Physics