Density Fluctuations in the Solar Wind Driven by Alfven Wave Parametric Decay

0496116 - ASÚ 2019 RIV GB eng J - Journal Article
Bowen, T.A. - Badman, S. - Hellinger, Petr - Bale, S. D.
Density Fluctuations in the Solar Wind Driven by Alfven Wave Parametric Decay.
Astrophysical Journal Letters. Roč. 854, č. 2 (2018), č. článku L33. ISSN 2041-8205. E-ISSN 2041-8213
R&D Projects: GA ČR(CZ) GA18-08861S
Institutional support: RVO:67985815
Keywords : instabilities * plasmas * solar wind
OECD category: Astronomy (including astrophysics,space science)
Impact factor: 8.374, year: 2018

Measurements and simulations of inertial compressive turbulence in the solar wind are characterized by anti-correlated magnetic fluctuations parallel to the mean field and density structures. This signature has been interpreted as observational evidence for non-propagating pressure balanced structures, kinetic ion-acoustic waves, as well as the MHD slow-mode. Given the high damping rates of parallel propagating compressive fluctuations, their ubiquity in satellite observations is surprising and suggestive of a local driving process. One possible candidate for the generation of compressive fluctuations in the solar wind is the Alfven wave parametric instability. Here, we test the parametric decay process as a source of compressive waves in the solar wind by comparing the collisionless damping rates of compressive fluctuations with growth rates of the parametric decay instability daughter waves. Our results suggest that generation of compressive waves through parametric decay is overdamped at 1 au, but that the presence of slow-mode-like density fluctuations is correlated with the parametric decay of Alfven waves.
Permanent Link: http://hdl.handle.net/11104/0288926