Magnetic field and ion velocity spectra in the solar wind from inertial to kinetic scales

Abstract

The paper analyzes the power spectra of solar wind velocity and magnetic field fluctuations that are computed in the frequency range around the break between inertial and kinetic scales. The study uses measurements of the Bright Monitor of the Solar Wind (BMSW) on board Spektr-R with a time resolution of 32 ms complemented with 10 Hz magnetic field observations from Wind propagated to the Spektr-R location and compare them with observations of Solar Orbiter and Parker Solar Probe closer to the Sun. We concentrate on the ion kinetic scale and investigate statistically the role of parameters like the fluctuation amplitudes of parallel and perpendicular magnetic field components, collisional age, temperature anisotropy or ion and electron beta. Our discussion encompasses the interplay of magnetic field and plasma fluctuations that characterize this dynamic environment and reveals that although the ion beta controls a position of the spectral break between the inertial and kinetic ranges, other mentioned parameters determine the steepness of the kinetic range spectrum of both quantities. We are showing that these statistical results are in line with theoretical considerations.