Inhomogeneous Distribution of High-Amplitude Kinetic Alfvén Waves in the Near-Sun Solar Wind

David Malaspina , Alexandros Chasapis , Peter Tatum , Chadi S. Salem , Stuart D. Bale , John W. Bonnell , Thierry Dudok de Wit (1) , Keith Goetz , Marc Pulupa , Jasper S. Halekas , Phyllis L. Whittlesey , Roberto Livi , Anthony W. Case , Michael Louis Stevens , Davin E. Larson

1 LPC2E - Laboratoire de Physique et Chimie de l'Environnement et de l'Espace

The near-Sun solar wind (sunward of 0.25 AU) is found to contain many intervals of high-amplitude electromagnetic broadband plasma waves. These waves are identified as kinetic Alfvén waves (KAWs) based on variation in their electric to magnetic field ratio and magnetic compressibility as a function of frequency. A key difference between these KAWs and KAWs observed near 1 AU is that the near-Sun high-amplitude KAWs are distributed unevenly in space, most often occurring where the ambient magnetic field deviates from the Parker spiral direction, including during magnetic switchbacks. Because small-scale turbulent fluctuations in the solar wind are often characterized as KAWs, these observations suggest that turbulent dissipation and heating via KAW fluctuations should also be spatially inhomogeneous in the near-Sun solar wind, maximizing in regions of high-amplitude KAWs. Also, a deviation between the observed KAWs and theoretical KAW behavior is observed at the smallest fluctuation scales. Possible origins of this deviation are explored.

Domains: Sciences of the Universe [physics]

David Malaspina, Alexandros Chasapis, Peter Tatum, Chadi S. Salem, Stuart D. Bale, et al.. Inhomogeneous Distribution of High-Amplitude Kinetic Alfvén Waves in the Near-Sun Solar Wind. AGU Fall Meeting 2022, 0000, à renseigner, Unknown Region. ⟨insu-04089874⟩