EGU22-10339, updated on 10 Jan 2024
EGU General Assembly 2022
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

The combined effect of electron and proton firehose instabilities for the solar wind plasma conditions

Rodrigo A. López1, Alfredo Micera2,3, Marian Lazar3,4, Shaaban M. Shaaban5, Stefaan Poedts3,6, and Giovanni Lapenta3
Rodrigo A. López et al.
  • 1Universidad de Santiago de Chile, Usach, Departamento de Física, Santiago, Chile (
  • 2Solar-Terrestrial Centre of Excellence - SIDC, Royal Observatory of Belgium, Brussels, Belgium
  • 3Centre for Mathematical Plasma Astrophysics, Department of Mathematics, KU Leuven, Celestijnenlaan 200B, B-3001 Leuven, Belgium
  • 4Institute for Theoretical Physics IV, Faculty for Physics and Astronomy, Ruhr-University Bochum, D-44780 Bochum, Germany
  • 5Theoretical Physics Research Group, Physics Department, Mansoura University, Mansoura, Egypt
  • 6Institute of Physics, University of Maria Curie-Sklodowska, Lublin, Poland

In the absence of collision, kinetic instabilities triggered by velocity space anisotropies of plasma particles play an essential role in limiting the deviations from isotropy. For example, in the solar wind, firehose instabilities may inhibit the growth of the temperatures in the direction parallel to the background magnetic field, counterbalancing the effect of the expansion. Electron and proton firehose instabilities can be triggered depending on the plasma parameters and the different branches within (periodic and aperiodic). Despite the significant difference between electron and proton spatial and temporal scales, both modes can work together to alter the dynamic of the plasma.
We use a fully kinetic 2D semi-implicit particle-in-cell simulation, iPic3D, to study the evolution and interplay of firehose instabilities triggered by electrons and protons when both species are anisotropic. The aperiodic electron firehose instability remains largely unaffected by the proton anisotropy and saturates rapidly at low-level fluctuations. On the other hand, the presence of anisotropic electrons has a considerable impact on the proton firehose modes, especially on the aperiodic branch, shifting the onset of the instability and boosting the saturation levels of the fluctuations. Anisotropic electrons contribute to more effective regulation of the proton anisotropy.

How to cite: López, R. A., Micera, A., Lazar, M., Shaaban, S. M., Poedts, S., and Lapenta, G.: The combined effect of electron and proton firehose instabilities for the solar wind plasma conditions, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-10339,, 2022.


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