Where and How?
Oh, how do solar astrophysicists wish they knew where and how do these solar particles get their energy! The general consensus is, however, that the energy of accelerated solar ions and electrons is derived from the magnetic fields that rise above sunspots. It is not just that magnetic fields are generally associated with particle acceleration, but also, no other available source could release energy so quickly.
While searching for an explanation of particle acceleration on the Sun,
British researchers in the 1950s, in particular Peter Sweet and James Dungey,
proposed the idea of magnetic reconnection, an idea later applied to the Earth's
magnetosphere and to substorms. Reconnection is still believed to be the energy source of flares and CMEs, but unfortunately, it seems to happen in the lower corona, where magnetic structures are invisible (with a few exceptions--see picture below). The nature of substorms and solar acceleration events may indeed be similar, though their scales differ greatly. However, satellites can be sent to substorms but not to the Sun, and therefore magnetospheric research may well hold clues to some of the problems of solar physics.