This open access book serves as a concise primer introducing the non-specialist reader to the
physics of solar energetic particles (SEP). It systematically reviews the evidence for the two
main mechanisms which lead to the so-called impulsive and gradual SEP events. This second
edition contains two completely new chapters discussing element abundances and shock waves
reflecting new theoretical modeling and observational results. Existing chapters have been
substantially expanded or updated with additions placed in a broader context. More specifically
the author discusses the timing of the onsets of SEPs their longitude distributions their
high-energy spectral shapes their correlations with other solar phenomena as well as the
all-important elemental and isotopic abundances. The book relates impulsive SEP events to
magnetic reconnection in solar flares and jets. The concept of shock acceleration by scattering
on self-amplified Alfvén waves is introduced as is the evidence of reacceleration of
impulsive-SEP material in the seed population accessed by the shocks in gradual events. The
text then develops processes of transport of ions out to an observer. Finally a technique to
determine the source plasma temperature in both impulsive and gradual events is
demonstrated.The author also mentions the role of SEP events as a radiation hazard in space and
briefly discusses the nature of the main particle telescope designs that have contributed to
most of the SEP measurements.
