Talk abstract

To study the particle acceleration at a magnetic null point (Null) in the solar corona, we calculate the self-consistent electromagnetic fields by 3-D MHD simulations (driven by photospheric plasma motion) and expose charged particles to these fields (the convective electric field and the magnetic field) near the Null within a full-orbit relativistic test-particle approach. The 3-D Null can, through its convective electric field and due to magnetic nonuniform drifts and de-magnetization, act as an effective accelerator for protons but not for electrons. Protons are more easily de-magnetized and accelerated because of their larger Larmor radii. For triggering significant acceleration of electrons, however, the existence of a resistive electric field that is mainly parallel to the magnetic field is required.