Spectrum of density fluctuations in the solar wind

Abstract

The power spectrum of density fluctuations in the solar wind and its relations with the spectra of the velocity and magnetic field fluctuations is investigated. The density fluctuations could behave as a passive scalar and be simply connected by velocity or the magnetic field fluctuations or they could dynamically participate in the joint production mechanism of all the fluctuations. The spectrum of the density fluctuations can distinguish between these two possibilities. Further, the inclusion of the Hall effect near the ion-material scale generates different spectra for the velocity and magnetic passive scalar, follow in such a case?. The answer leads to the interesting consequence that the electron density fluctuations and the ion density fluctuations have different spectra at spatial scales equal to and smaller than the ion-material scale. This result clearly demonstrates the two-fluid picture brought in by the Hall effect.