On the Fermi Acceleration Process at Curvilinear Shock Fronts

We present results of hybrid particle-in-cell simulation of ions 1st order Fermi acceleration at a curvilinear shock front. Using the example of the global model of the Earth’s bow shock, the efficiency of particles injection into the Fermi acceleration process is investigated depending on their impact parameter. It is shown that Fermi acceleration and the formation of a foreshock occur only in quasi-parallel regions. Meanwhile, particles can be injected and gain initial energy in quasi-perpendicular regions through the shock drift acceleration mechanism, and then enter the Fermi acceleration region. Suprathermal particles generated near the quasi-parallel front regions can subsequently propagate along the front to quasi-perpendicular regions. The fraction of particles injected into the acceleration process near the subsolar point of the Earth’s bow shock reaches 20 $$\%$$ . The model allows for the identification of features of the Fermi acceleration process on curvilinear shocks that are significant for application to astrophysical shocks of various scales.