Solar Wind Turbulence Studies using MMS Fast Plasma Investigation Data

TL;DR

This paper presents the first analysis of solar wind turbulence using high-resolution ion and electron velocity moments from MMS data, revealing kinetic range properties and scale-dependent fluctuation behaviors.

Contribution

It introduces a novel frequency domain Hampel filter for processing high-resolution plasma data and extends turbulence analysis into the kinetic range.

Findings

Magnetic fluctuations dominate across energy-containing and inertial ranges.

Electron velocity fluctuations surpass ion velocity at scales below the ion-inertial length.

Ion velocity kurtosis peaks near ion-inertial scales and becomes Gaussian at smaller scales.

Abstract

Studies of solar wind turbulence traditionally employ high-resolution magnetic field data, but high-resolution measurements of ion and electron moments have been possible only recently. We report the first turbulence studies of ion and electron velocity moments accumulated in pristine solar wind by the Fast Particle Investigation instrument onboard the Magnetospheric Multiscale (MMS) Mission. Use of these data is made possible by a novel implementation of a frequency domain Hampel filter, described herein. After presenting procedures for processing of the data, we discuss statistical properties of solar wind turbulence extending into the kinetic range. Magnetic field fluctuations dominate electron and ion velocity fluctuation spectra throughout the energy-containing and inertial ranges. However, a multi-spacecraft analysis indicates that at scales shorter than the ion-inertial length, electron velocity fluctuations become larger than ion velocity and magnetic field fluctuations. The kurtosis of ion velocity peaks around few ion-inertial lengths and returns to near gaussian value at sub-ion scales.