Parker Solar Probe Observations of Proton Beams Simultaneous with Ion-scale Waves

Author
Keywords
Abstract
<p>Parker Solar Probe (PSP), NASA\textquoterights latest and closest mission to the Sun, is on a journey to investigate fundamental enigmas of the inner heliosphere. This paper reports initial observations made by the Solar Probe Analyzer for Ions (SPAN-I), one of the instruments in the Solar Wind Electrons Alphas and Protons instrument suite. We address the presence of secondary proton beams in concert with ion-scale waves observed by FIELDS, the electromagnetic fields instrument suite. We show two events from PSP\textquoterights second orbit that demonstrate signatures consistent with wave-particle interactions. We showcase 3D velocity distribution functions (VDFs) measured by SPAN-I during times of strong wave power at ion scales. From an initial instability analysis, we infer that the VDFs departed far enough away from local thermodynamic equilibrium to provide sufficient free energy to locally generate waves. These events exemplify the types of instabilities that may be present and, as such, may guide future data analysis characterizing and distinguishing between different wave-particle interactions.</p>
Year of Publication
2020
Journal
The Astrophysical Journal Supplement Series
Volume
248
Number
Number of Pages
5
Date Published
05/2020
URL
https://iopscience.iop.org/article/10.3847/1538-4365/ab86afhttps
DOI
10.3847/1538-4365/ab86af