Journal cover Journal topic
Annales Geophysicae An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 1.621 IF 1.621
  • IF 5-year value: 1.614 IF 5-year 1.614
  • CiteScore value: 1.61 CiteScore 1.61
  • SNIP value: 0.900 SNIP 0.900
  • SJR value: 0.910 SJR 0.910
  • IPP value: 1.58 IPP 1.58
  • h5-index value: 24 h5-index 24
  • Scimago H index value: 80 Scimago H index 80
Volume 29, issue 5
Ann. Geophys., 29, 909-917, 2011
https://doi.org/10.5194/angeo-29-909-2011
© Author(s) 2011. This work is distributed under
the Creative Commons Attribution 3.0 License.
Ann. Geophys., 29, 909-917, 2011
https://doi.org/10.5194/angeo-29-909-2011
© Author(s) 2011. This work is distributed under
the Creative Commons Attribution 3.0 License.

  25 May 2011

25 May 2011

Apparent temperature anisotropies due to wave activity in the solar wind

D. Verscharen1,2 and E. Marsch1 D. Verscharen and E. Marsch
  • 1Max Planck Institute for Solar System Research, Max-Planck-Str. 2, 37191 Katlenburg-Lindau, Germany
  • 2Institute for Theoretical Physics, TU Braunschweig, Mendelssohnstr. 3, 38106 Braunschweig, Germany

Abstract. The fast solar wind is a collisionless plasma permeated by plasma waves on many different scales. A plasma wave represents the natural interplay between the periodic changes of the electromagnetic field and the associated coherent motions of the plasma particles. In this paper, a model velocity distribution function is derived for a plasma in a single, coherent, large-amplitude wave. This model allows one to study the kinetic effects of wave motions on particle distributions. They are by in-situ spacecraft measured by counting, over a certain sampling time, the particles coming from various directions and having different energies. We compare our results with the measurements by the Helios spacecraft, and thus find that by assuming high wave activity we are able to explain key observed features of the measured distributions within the framework of our model. We also address the recent discussions on nonresonant wave–particle interactions and apparent heating. The applied time-averaging procedure leads to an apparent ion temperature anisotropy which is connected but not identical to the intrinsic temperature of the underlying distribution function.

Publications Copernicus
Download
Citation
Share