Kinetic Scale Slow Solar Wind Turbulence in the Inner Heliosphere: Co-existence of Kinetic Alfvén Waves and Alfvén Ion Cyclotron Waves

Abstract

The nature of the plasma wave modes around the ion kinetic scales in highly Alfvénic slow solar wind turbulence is investigated using data from the NASA's Parker Solar Probe taken in the inner heliosphere, at 0.18 Astronomical Unit (AU) from the sun. The joint distribution of the normalized reduced magnetic helicity ${\sigma }_m({\theta }_{RB},\tau )$ is obtained, where ${\theta }_{RB}$ is the angle between the local mean magnetic field and the radial direction and $\tau$ is the temporal scale. Two populations around ion scales are identified: the first population has ${\sigma }_m({\theta }_{RB},\tau )<0$ for frequencies (in the spacecraft frame) ranging from 2.1 to 26 Hz for $60^{\circ }<{\theta }_{RB}<130^{\circ }$, corresponding to kinetic Alfvén waves (KAWs), and the second population has ${\sigma }_m({\theta }_{RB},\tau )>0$ in the frequency range [1.4, 4.9] Hz for ${\theta }_{RB}>150^{\circ }$, corresponding to Alfvén ion Cyclotron Waves (ACWs). This demonstrates for the first time the co-existence of KAWs and ACWs in the slow solar wind in the inner heliosphere, which contrasts with previous observations in the slow solar wind at 1 AU. This discrepancy between 0.18 and 1 AU could be explained, either by i) a dissipation of ACWs via cyclotron resonance during their outward journey, or by ii) the high Alfvénicity of the slow solar wind at 0.18 AU that may be favorable for the excitation of ACWs.

References in corpus (30)

• Double-slit photoelectron interference in strong-field ionization of the neon dimer
• Astrophysical gyrokinetics: kinetic and fluid turbulent cascades in magnetized weakly collisional plasmas
• Measurement of the electric fluctuation spectrum of magnetohydrodynamic turbulence
• Anisotropic scaling of magnetohydrodynamic turbulence
• Gyrokinetic Simulations of Solar Wind Turbulence from Ion to Electron Scales
• Switchbacks in the near-Sun magnetic field: long memory and impact on the turbulence cascade
• Dependence of solar wind power spectra on the direction of the local mean magnetic field
• The Solar Probe Cup on Parker Solar Probe
• A prescription for the turbulent heating of astrophysical plasmas
• Scaling of the electron dissipation range of solar wind turbulence
• Ion Scale Electromagnetic Waves in the Inner Heliosphere
• On the Existence of the Kolmogorov Inertial Range in the Terrestrial Magnetosheath Turbulence
• Magnetospheric Multiscale Observations of Electron Vortex Magnetic Hole in the Magnetosheath Turbulent Plasma
• New insight into short wavelength solar wind fluctuations from Vlasov theory
• Density Fluctuation Spectrum of Solar Wind Turbulence between Ion and Electron Scales
• Spectral Slope Variation at Proton Scales from Fast to Slow Solar Wind
• Alfven Wave Turbulence and Perpendicular Ion Temperatures in Coronal Holes
• The Role of Proton-Cyclotron Resonance as a Dissipation Mechanism in Solar Wind Turbulence: A Statistical Study at Ion-Kinetic Scales
• On slow solar wind with high Alfvénicity: from composition and microphysics to spectral properties
• Cross Helicity Reversals In Magnetic Switchbacks
• On the Interpretation of Magnetic Helicity Signatures in the Dissipation Range of Solar Wind Turbulence
• Energy cascade rate measured in a collisionless space plasma with MMS data and compressible Hall magnetohydrodynamic turbulence theory
• Spectral Features of Magnetic Fluctuations at Proton Scales from Fast to Slow Solar Wind
• Physical Interpretation of the Angle Dependent Magnetic Helicity Spectrum in the Solar Wind: The Nature of Turbulent Fluctuations near the Proton Gyroradius Scale
• Diagnosing solar wind origins using in-situ measurements in the inner heliosphere
• Observational Test of Stochastic Heating in Low-$\beta$ Fast Solar Wind Streams
• Parallel-propagating Fluctuations at Proton-kinetic Scales in the Solar Wind are Dominated by Kinetic Instabilities
• The origin of slow Alfvénic solar wind at solar minimum
• Kinetic Alfvén turbulence below and above ion-cyclotron frequency
• Occurrence Rates and Heating Effects of Tangential and Rotational Discontinuities as Obtained from Three-dimensional Simulation of Magnetohydrodynamic Turbulence

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• The evolution of compressible solar wind turbulence in the inner heliosphere: PSP, THEMIS and MAVEN observations
• Characteristics of Magnetic Holes in the Solar Wind Revealed by Parker Solar Probe
• The Radial Distribution of Ion-scale Waves in the Inner Heliosphere
• The incompressible energy cascade rate in anisotropic solar wind turbulence
• Proton and electron temperatures in the solar wind and their correlations with the solar wind speed
• Anisotropy of Magnetic Field Spectra at Kinetic Scales of Solar Wind Turbulence as Revealed by Parker Solar Probe in the Inner Heliosphere
• A Statistical Study of the Compressible Energy Cascade Rate in Solar Wind Turbulence: Parker Solar Probe Observations
• Magnetic helicity signature and its role in regulating magnetic energy spectra and proton temperatures in the solar wind
• Growth of Outward Propagating Fast-Magnetosonic/Whistler Waves in the Inner Heliosphere Observed by Parker Solar Probe
• The effects of finite electron inertia on helicity-barrier-mediated turbulence
• Turbulent heating in collisionless low-beta plasmas: imbalance, Landau damping, and electron-ion energy partition
• The role of the thermal properties of electrons on the dispersion properties of Alfvén waves in space plasmas