Observation of an MHD Alfvén vortex in the slow solar wind

Abstract

In the solar wind, magnetic field power spectra usually show several power-laws. In this paper, magnetic field data from the Cluster mission during an undisturbed interval of slow solar wind is analyzed at 0.28Hz, near the spectral break point between the ion inertial and dissipation/dispersion ranges. Assuming Taylor's frozen-in condition, it corresponds to a proton kinetic scale of $k{v}_A/{\Omega }_p\sim 0.38$, where $v_A$ and ${\Omega }_p$ are the Alfvén speed and proton angular gyrofrequency, respectively. Data show that the Cluster spacecraft passed through a series of wavepackets. A strong isolated wavepacket is found to be in accordance with the four Cluster satellites crossing an Alfvén vortex, a nonlinear solution to the incompressible MHD equations. A strong agreement is seen between the data from four satellites and a model vortex with a radius of the order of $40$ times the local proton gyro-radii. The polarization at different spacecraft is compared and is found to agree with the vortex model, whereas it cannot be explained solely by the linear plane wave approach.

arXiv commentSubmitted

References in corpus (8)

• Universality of solar wind turbulent spectrum from MHD to electron scales
• Anisotropic scaling of magnetohydrodynamic turbulence
• Dependence of solar wind power spectra on the direction of the local mean magnetic field
• Anisotropy of Solar Wind Turbulence between Ion and Electron Scales
• Power and spectral index anisotropy of the entire inertial range of turbulence in the fast solar wind
• Solar wind turbulent spectrum at plasma kinetic scales
• Coherent events and spectral shape at ion kinetic scales in the fast solar wind turbulence
• Kinetic plasma turbulence in the fast solar wind measured by Cluster

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• Magnetospheric Multiscale Observation of Kinetic Signatures in the Alfvén Vortex
• Variability Of The Magnetic Field Power Spectrum In The Solar Wind At Electron Scales
• Small-scale Magnetic Flux Ropes with Field-aligned Flows via the PSP In-situ Observations
• Contribution of Magnetic Reconnection Events to Energy Dissipation in Magnetosheath Turbulence
• Statistical analysis of stochastic magnetic fluctuations in space plasma based on the MMS mission
• Kinetic turbulence in space plasmas observed in the near-Earth and near-Sun solar wind
• Chaos and complexity in the dynamics of nonlinear Alfvén waves in a magnetoplasma
• Ion-Scale Solitary Structures in the Solar Wind Observed by Solar Orbiter and Parker Solar Probe