Solar energetic particles (SEPs). The Sun produces very energetic particles during solar eruptions, i.e., solar flares and coronal mass ejections (CMEs). These outburst of energetic particles are called SEP events or solar particle events. Because they can penetrate thick layers of material, SEPs constitute a severe radiation risk to humans and electronics in space. Together with my research group and collaborators, I study the acceleration of SEPs close to the Sun and their transport in the interplanetary medium to near-Earth space and beyond, as well as the near-Earth radiation environment generated by SEPs.

Shock waves are transitions from supersonic to subsonic flow associated with compression (i.e., increase of density) and dissipation (i.e., conversion of ordered kinetic energy of the flow to random thermal energy). In ordinary gases, shocks have thicknesses of the order of the collisional mean free path of the molecular motion. In dilute space plasmas, binary collisions are too infrequent to account for the dissipation and re-distribution of energy. Instead, collective processes involving fluctuating electromagnetic fields take the role of collisions. Such shocks are termed collisionless shocks. In the absence of binary collisions, collisionless shocks generate energetic particle populations (such as SEPs) and together with my research group and collaborators, I focus on understanding this acceleration process in detail.