Implications of Near Solar Source Pickup Ions

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The investigators will study major heliospheric pickup ion sources in the solar wind, their propagation and acceleration. Pickup ions are generated from neutral atoms when they become ionized and begin to gyrate in a plasma's magnetic field. In the case of the solar wind, pickup ions born from slowly moving neutrals acquire an initial speed nearly equal to the solar wind speed as they are transported out with the solar wind's magnetic field. The pickup process thereby creates a more energetic and therefore more easily observed population of ions that may be used to infer properties of the neutral environment from which they were created. In the heliosphere, there are three main populations of pickup ions: interstellar pickup ions from interstellar neutrals, inner source pickup ions created by interactions between interplanetary dust and the solar wind, and discrete source pickup ions from comets, planets, and other discrete sources. The investigators will characterize near-solar pickup ion sources by modeling distribution functions and hydrodynamic properties of pickup ions produced from near-solar and interstellar sources. They will also study the relative significance of near-solar source pickup ions, interstellar source pickup ions, and solar wind particles as seed populations for energetic particles and anomalous cosmic rays.