Identifying Current-Sheet-like Structures in the Solar Wind

Abstract

In past years, measurements of the solar wind plasma have advanced our understanding of MHD turbulence tremendously. At small scales, the solar wind is believed to be ve`xry multifractal with nonlinear interactions causing an intermittent energy dissipation, leading to possible current-sheet structures. In this Letter, we propose a systematic data analysis procedure to examine the existence of current sheets in the solar wind. We show that by studying the integrated distribution function F(θ , ζ) of the angle between two unit magnetic fields \hat{\boldsymbol{b}}(t) and \hat{\boldsymbol{b}}(t+\zeta) , as well as its ζ-dependence, one can unambiguously identify the existence of current-sheet-like structures in the solar wind. Using this procedure, we analyze magnetic field data from the VHM/FGM instrument on board the spacecraft Ulysses for two periods, one in solar maximum and the other in solar minimum. In both cases, current sheets are clearly inferred. Furthermore, we also outline a procedure that allows the identification of the actual locations of these current sheets. Results from our analysis and the implications of the existence of current sheets in the solar wind are discussed.