Ion acceleration at three dimensional magnetohydrodynamic shocks

Summary form only given. We compare the results from analytical and numerical computations of various characteristic parameters of a pre-existing population after its interaction with a model 3-D magnetohydrodynamic shock, through shock drift acceleration (SDA), with magnetic field and superthermal ion measurements obtained by a series of spacecraft (IMP-8, ISEE-1 and 2, Ulysses, Voyager-1 and 2) near perpendicular (where the magnetic field lines are parallel to the shock front) or quasi-perpendicular regions of the Earth's and Jupiter's bow shock. In particular we study intensity-time profiles, energy spectra, anisotropies of angular distributions and reflection transmission coefficient of energetic ions. We found that the observational characteristics agree with the predictions of SDA mechanism and that the acceleration efficiency strongly depends on the shape of the 3-D shock, i.e. ions are accelerated to higher energies at Jupiter's than at Earth's bow shock.