Advancing our understanding of impulsive SEP events via Inner Heliospheric Sentinels

SEP events are normally classified as Gradual and Impulsive. Energetic particles (electrons and ions) from impulsive SEP events are believed to be accelerated at flare sites during a short period of time and then propagate into the interplanetary medium. The observed time intensity profiles and anisotropies of electrons and ions in impulsive events are the results of combined effects of injection at the Sun and the propagation of energetic particles in the solar wind. To discern the effects of propagation from that of injection, observations at multiple heliocentric distances are crucial. The Sentinels project, including 4 Inner Heliospheric Sentinels spacecraft, will provide valuable dataset of energetic particles at distances from 0.25 AU to 1.0 AU, thus allowing one to better understand the propagation effect and constrain the injection profile. In this work, we investigate how the time-intensity profiles and anisotropies of energetic particles in impulsive events vary as a function of heliocentric distance. We concentrate our study on almost "scatter-free" events since the propagation effects in these events are the easiest to deduce. By assuming pitch angle scattering as the main agent of the wave-particle interaction between propagating energetic particles and the solar wind magnetic turbulence, we can relate the width of the observed time intensity profiles to the strength of the turbulence (and thus diffusion coefficient). We note that our simulation (for high energy electrons) can be used to investigate the properties of the magnetic turbulence, as a function of distance, in quiet solar wind. This again, can be compared with Sentinels observations, and will advance our understanding of the quiet solar wind turbulence.