Temperature-anisotropy-driven instabilities and electron and ion energy budget in the expanding solar wind: fully-kinetic Expanding Box Model simulations with EB-iPic3D
Abstract
Observations (Matteini et al, 2013; Stverak et al, 2008 ), analytical work (Yoon 2017), simulations (Matteini et al 2006, Hellinger et al 2008, Innocenti et al, sub) point to the role of kinetic instabilities in constraining the bulk parameters of the ion and electron populations in the solar wind. In particular, ion and electron firehose instabilities constrain solar wind observations in the Tperp< Tpar regime, towards which the solar wind is pushed by spherical plasma expansion.
Analytical work (Yoon et al 2017) and simulations (Micera et al, sub) point to temperature-anisotropy-driven instabilities as a mean for energy exchange between ions and electrons. This would be consistent with the electron and ion temperature evolution as a function of the heliocentric distance, which highlights the need for a positive and negative energy balance for ions and electrons to explain observed trends (Stverak et al, 2015). We investigate these dynamics through fully kinetic simulations where ion and electron temperature-anisotropy-induced kinetic instabilities develop self consistently as a result of solar wind expansion. The simulations are carried out with EB-iPic3D (Innocenti et al, 2019), a semi-implicit, Expanding Box, fully kinetic code. Our simulations allow us to investigate in details the electron/ion energy exchange and the trajectory of a solar wind plasma parcel in the ßpar vs Tperp/Tpar plane, as a function of the heliocentric distance. They also show that, under certain solar wind conditions, the thermal anisotropy triggering the electron firehose instability is drastically reduced by the instability itself through the generation of short-scale, short-lived, complex electron velocity distribution patterns. Hellinger,P.,& Travnıcek,P.M.2008, JGR: SP, 113 Innocenti, M. E., Tenerani, A., & Velli, M. 2019, APJ, 870, 66 Innocenti, M.E., Tenerani, A., Boella, E.,& Velli, M. Submitted Matteini, L., Landi, S., Hellinger, P., & Velli, M. 2006, JGR: SP, 111 Matteini, L., Hellinger, P., Goldstein, B. E., et al. 2013,JGR: SP, 118, 2771 Micera A., Boella E., Zhukov, A. N., Shaaban, S. M., Lazar M., & Lapenta, G., arXiv:1907.08502 Stverak, S., Travnıcek, P., Maksimovic, M., et al. 2008,JGR: SP, 113 Stverak, S., Travnıcek, P. M., & Hellinger, P. 2015,JGR: SP, 120, 8177 Yoon, P. H., & Sarfraz, M. 2017, ApJ, 835, 246- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMSH52A..04I
- Keywords:
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- 2164 Solar wind plasma;
- INTERPLANETARY PHYSICS;
- 2169 Solar wind sources;
- INTERPLANETARY PHYSICS;
- 7509 Corona;
- SOLAR PHYSICS;
- ASTROPHYSICS;
- AND ASTRONOMY;
- 7863 Turbulence;
- SPACE PLASMA PHYSICS