On the multifractality of plasma turbulence in the solar wind

Abstract:

The upper atmosphere of the Sun is continuously releasing a stream of charged particles which constitutes the solar wind. This ejected plasma gives an extent of interesting phenomena in plasma physics. One of the fundamental problems in this area is the understanding of the relaxation process in collisionless plasma, and the resultant state of the electromagnetic turbulence, in particular, at kinetic scales.

In this work we have analyzed turbulent plasma in the kinetic scale by the characterization of magnetic fluctuations time series. Considering numerical Particle-In-Cell (PIC) simulations we apply a method known as MultiFractal Detrended Fluctuation Analysis (MFDFA) to study the fluctuations of solar-wind-like plasmas in thermodynamic equilibrium (represented by Maxwellian velocity distribution functions), and out of equilibrium plasma represented by Tsallis velocity distribution functions, characterized by the kappa (κ) parameter, to establish relations between the fractality of magnetic fluctuation and the kappa parameter.

The motivation of this research is to characterize turbulent plasmas through time series analysis using the MFDFA method, with the objective of describe the dependence associated to different velocity distribution functions. In particular, we explore the relations between the multifractality of magnetic fluctuations time series, extracted from the simulations, and the kappa parameter. We expect our analysis to be useful for the characterization of the electromagnetic turbulence in collisionless space plasmas, such as the solar wind, and this tool to be useful to extract valuable information about the plasma when high resolution particle detectors are not available.