Relationship between high-energy particles and ion flux in the magnetosheath

Abstract

The role of high-energy particles in upstream bow shock regions is well known in connection of reflected and accelerated particles leading to wave excitation and creation of different types of disturbances. However, observations of these particles in a particular point within the magnetosheath is not reported so often. During five years, INTERABALL-1 spent regularly long time intervals within the magnetosheath, predominantly in flank regions. We are using a set of magnetosheath observations of the total plasma flux, its fluctuations, and the flux of energetic particles with motivation to find the mutual connection among the mentioned quantities. We present simultaneous observations of plasma and energetic particle fluxes and indicate a probability of their observations as a function of configuration of the interplanetary magnetic field. Our statistical survey suggests that the presence of high-energy particles influences the total ion flux only weakly and under specific circumstances. On the other hand, the coupling between high-energy particles and ion flux fluctuation level seems to be stronger. From our analysis further follows that (1) a majority of energetic ions within the magnetosheath originate in the dayside foreshock and ions are swept antisunward; (2) both the upstream and nearby foreshock regions contribute to fluctuations in the nightside magnetosheath plasma flux; (3) the plasma flux increases downstream from the quasiparallel bow shock; and (4) the fluxes of plasma and energetic ions exhibit an anticorrelation near the magnetopause behind the quasiparallel bow shock.