Solar Energetic Particles
  23rd Solar Cycle

The most complete measurements of elemental abundances in the solar corona come from measurements of high energy particles accelerated in the large Solar Energetic Particle (SEP) events.
Initially it was thought that the energetic particles in large SEP events were accelerated in solar flares. In recent years, however, it has become clear that in the large gradual events particles are accelerated at shock waves that are driven out from the Sun by Coronal Mass Ejections (CMEs). These shocks accelerate the ions of the chemical elements in a fairly equivalent manner. In contrast, particles accelerated in impulsive solar flares show specific elemental enhancements produced by resonant wave-particle interactions during stochastic acceleration of the ions from the flare plasma.
Solar flare particle spectra
New spacecraft observations can extend Solar Energetic Particle measurements to heavier elements, to rarer elements and to isotopes. NINA can perform SEP observations in the polar sectors of the orbit for a relatively long period of the 23rd solar cycle. Its good mass discrimination can help in the determination of their composition and therefore in the comprehension of the sources and acceleration mechanisms involved.

Sep Event
SEP Event
SEP Event