Non-axisymmetric Anisotropy of magnetic field fluctuations in the solar wind dissipation range

Details Non-axisymmetric Anisotropy of magnetic field fluctuations in the solar wind dissipation range Non-axisymmetric Anisotropy of magnetic field fluctuations in the solar wind dissipation range

Dec 2011

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011agufmsh52a..04g&link_type=abstract

American Geophysical Union, Fall Meeting 2011, abstract #SH52A-04

Physics

[2164] Interplanetary Physics / Solar Wind Plasma

Scientific paper

Anisotropy is a key topic for theoretical, numerical and observational studies of plasma turbulence in the solar wind. A fundamental assumption of many theoretical descriptions of turbulence, both in the inertial and dissipation range, is that of axisymmetry of the anisotropic fluctuations with respect to the background magnetic field. Intriguingly, there is observational evidence that these fluctuations are ordered both with respect to the background field and flow directions. This level of non-axisymmetry is observed to increases as we move from the inertial range to the dissipation range. This is characterized by minimum variance analysis as well as in observations of the ratio of the Power Spectral Density (PSD) in the perpendicular directions, eBxeR : eBx(eBxeR), where eB is a unit vector in the direction of the average magnetic field and eR is a unit vector in the radial direction away from the sun. Here, we show that this observed non-axisymmetry may arise as a data sampling effect rather than as a result of the physical properties of the turbulent plasma. We first quantify the observed non-axisymmetry through the inertial and dissipation ranges via the PSD ratio in the perpendicular plane for in-situ measurements using the Cluster spacecraft in fast wind where both magnetic field instruments, FGM and STAFF, are operating in burst mode. This allows the small scales of the dissipation range to be investigated. We then show that a spacecraft 'fly through' of a simple analytical model for a field composed of a linear superposition of transverse waves, where Taylor's hypothesis is used and the only variable parameter is the power law index, is sufficient to give the observed non-axisymmetry. In particular, we find that the ratio of power in the perpendicular plane, eBxeR : eBx(eBxeR), depends on the exponent of the PSD. Thus we find that the enhanced non-axisymmetry seen in the dissipation range is a result of the steepening of the PSD slope.

Affiliated with

Also associated with

No associations

Rating

Non-axisymmetric Anisotropy of magnetic field fluctuations in the solar wind dissipation range does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.

If you have personal experience with Non-axisymmetric Anisotropy of magnetic field fluctuations in the solar wind dissipation range, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Non-axisymmetric Anisotropy of magnetic field fluctuations in the solar wind dissipation range will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFWR-SCP-O-881169