arXiv subjects

Roberto Bruno

Publications and source records attributed to Roberto Bruno.

39 records · Page 3Linked to original sources

arXiv2006

Persistence of small-scale anisotropy of magnetic turbulence as observed in the solar wind

The anisotropy of magnetophydrodynamic turbulence is investigated by using solar wind data from the Helios 2 spacecraft. We investigate the behaviour of the complete high-order moment tensors of magnetic field increments and we compare the usual longitudinal structure functions which have both isotropic and anisotropic contributions, to the fully anisotropic contribution. Scaling exponents have been extracted by an interpolation scaling function. Unlike the usual turbulence in fluid flows, small-scale magnetic fluctuations remain anisotropic. We discuss the radial dependence of both anisotropy and intermittency and their relationship.

physics.space-ph↗

arXiv2004

One-point statistics and intermittency of induced electric field in the solar wind

The interplanetary induced electric field e=vxb is studied, using solar wind time series. The probability distribution functions (PDFs) of the electric field components are measured from the data and their non-gaussianity is discussed. Moreover, for the first time we show that the electric field turbulence is characterized by intermittency. This point is addressed by studying, as usual, the scaling of the PDFs of field increments, which allows a quantitative characterization of intermittency.

physics.space-ph↗

arXiv1999

Intermittency in the solar wind turbulence through probability distribution functions of fluctuations

Intermittency in fluid turbulence can be emphasized through the analysis of Probability Distribution Functions (PDF) for velocity fluctuations, which display a strong non-gaussian behavior at small scales. Castaing et al. (1990) have introduced the idea that this behavior can be represented, in the framework of a multiplicative cascade model, by a convolution of gaussians whose variances is distributed according to a log-normal distribution. In this letter we have tried to test this conjecture on the MHD solar wind turbulence by performing a fit of the PDF of the bulk speed and magnetic field intensity fluctuations calculated in the solar wind, with the model. This fit allows us to calculate a parameter depending on the scale, which represents the width of the log-normal distribution of the variances of the gaussians. The physical implications of the obtained values of the parameter as well as of its scaling law are finally discussed

physics.plasm-ph↗