Parker Solar Probe observations of proton beams simultaneous with ion-scale waves

Abstract

Parker Solar Probe (PSP), NASA's 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 (SWEAP) 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's 2nd 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 (LTE) 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.

24 pages, 9 figures, 2 tables

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Cited by in corpus (35)

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• The In Situ Signature of Cyclotron Resonant Heating
• Switchbacks: statistical properties and deviations from alfvénicity
• Enhanced proton parallel temperature inside patches of switchbacks in the inner heliosphere
• Inferred Linear Stability of Parker Solar Probe Observations using One- and Two-Component Proton Distributions
• Inner-Heliosphere Signatures of Ion-Scale Dissipation and Nonlinear Interaction
• Strong perpendicular velocity-space in proton beams observed by Parker Solar Probe
• Statistical analysis of orientation, shape, and size of solar wind switchbacks
• The Electromagnetic Signature of Outward Propagating Ion-Scale Waves
• Proton Core Behaviour Inside Magnetic Field Switchbacks
• The Radial Distribution of Ion-scale Waves in the Inner Heliosphere
• On quasi-parallel whistler waves in the solar wind
• Modeling ion beams, kinetic instabilities, and waves observed by the Parker Solar Probe near perihelia
• The Structure and Origin of Switchbacks: Parker Solar Probe Observations
• Wave-particle energy transfer directly observed in an ion cyclotron wave
• Ion-Driven Instabilities in the Inner Heliosphere I: Statistical Trends
• Magnetic reconnection as a mechanism to produce multiple protonpopulations and beams locally in the solar wind
• Estimation of turbulent proton and electron heating rates via Landau damping constrained by Parker Solar Probe observations
• Parker Solar Probe Observations of High Plasma Beta Solar Wind from Streamer Belt
• Electromagnetic Proton Beam Instabilities in the Inner Heliosphere: Energy Transfer Rate, Radial Distribution, and Effective Excitation
• Cross Helicity and the Helium Abundance as an in situ Metric of Solar Wind Acceleration
• Fully Kinetic Simulations of Proton-Beam-Driven Instabilities from Parker Solar Probe Observations
• The Temperature, Electron, and Pressure Characteristics of Switchbacks: Parker Solar Probe Observations
• Magnetic reconnection-driven energization of protons up to 400 keV at the near-Sun heliospheric current sheet
• Modeling hot, anisotropic ion beams in the solar wind motivated by the Parker Solar Probe observations near perihelia
• Growth of Outward Propagating Fast-Magnetosonic/Whistler Waves in the Inner Heliosphere Observed by Parker Solar Probe
• The Evolution of Heavy Ion Abundances with Solar Activity
• Decoding the formation of hammerhead ion populations observed by Parker Solar Probe
• A Tale of Two Shocks
• Characterizing the Impact of Alfvén Wave Forcing in Interplanetary Space on the Distribution of near-Earth Solar Wind Speeds
• Evolution of an Alfvén Wave-Driven Proton Beam in the Expanding Solar Wind
• On the Regulation of the Solar Wind Helium Abundance by the Hydrogen Compressibility
• Scope and limitations of ad hoc neural network reconstructions of solar wind parameters
• Hybrid simulations of the proton beam instabilities in the young solar wind. The formation of hammerhead-like distributions