Medium energy proton fluxes outside the magnetopause: INTERBALL-1 data Original Research Article

The extensive data set of the DOK2 energetic proton measurements indicates a decrease of flux at 22 – 29 keV based on the distance from the magnetopause within the magnetosheath. In the region upstream from the bow shock the signatures expected for the preferential acceleration of protons at quasiparallel shocks are found in the data. In addition to the proton leakage from the magnetosphere observed in several experiments, the observations confirm the importance of bow shock acceleration for the population of medium energy protons in the near upstream region.