Observations of Electromagnetic Fluctuations at Ion Kinetic Scales in the Solar Wind

Abstract

Wavelet techniques enable reduced power spectra and cross-spectra to be analyzed as a function of the angle θ _BV formed by the scale dependent local mean magnetic field B ₀ and the flow direction of the solar wind. These techniques allow the data along a line oriented at any angle θ _BV to B ₀ to be isolated and studied independently thus providing new information about the properties of the fluctuations along directions parallel, perpendicular, and at arbitrary angles to the local mean magnetic field. Recent investigations of the normalized magnetic helicity spectrum σ _m using this technique have revealed the existence of two distinct populations of fluctuations near the proton inertial length scale, that is, at wavenumbers near kc/{ω }_{pp} = 1. These observations and their physical interpretation are briefly reviewed.