Plasma Kinetics in the Inner Heliosphere and the NASA Solar Probe Plus Mission
Stuart Bale



I will describe measurements of plasma velocity distribution functions in the solar wind at 1 AU using instruments on NASA's WIND spacecraft. Three distinct populations of electrons are observed and the collisional coupling between the cool, dense 'core' electron population and the solar wind protons can be observed directly. This Coulomb coupling relationship can be used probe the electron distribution of the solar corona and suggests that the coronal electron population will be highly nonthermal. Ion measurements also show signatures of kinetics and may actively drive local instabilities. I will also describe the NASA Solar Probe Plus mission, which will launch in 2018 and orbit the Sun with a final perihelion altitude of 9.8 solar radii, well within the predicted Alfven surface. Solar Probe Plus will make the first ever in situ measurements of plasma heating processes in the solar corona.