Accelerated particles from turbulent boundary layer Original Research Article

We study the high latitude turbulent boundary layer (TBL), where the essential magnetosheath (MSH) ion heating (in 1.5–3 times) is seen in more than 80 % cases within ‘diamagnetic bubbles’ -structures with highly reduced magnetic field. The high- energy tails of the core particle distributions in TBL exceed 20keV for ions and 10keV for electrons on April 21, 1996. We find indications also for further acceleration of a small fraction of protons there up to 300 keV. More energetic particles could have maximum intensity just inside magnetopause that is consistent with their magnetospheric origin. Simultaneous Polar and Interball-1 data in TBL and MSH on May 29, 1996 demonstrate heating of the MSH core ions in cusp, TBL and stagnant MSH. In the TBL the O+ ions might be heated as well (up to few keV) and even be backscattered towards the ionosphere together with the protons > 18 keV. The dominant incompressible Alfvenic waves in TBL constitute an intermediate chain for the transformation of the solar wind kinetic energy into the auroral particle acceleration/heating. The most intensive energy transformation occurs over cusps and along the boundary between the mantle and low latitude boundary layer down to X= − 6 RE. It provides primary heating for MSH ions in both cusp proper and boundary cusp.