Kinetic cascade nature: Cluster and MMS observations in the solar wind and Earth's magnetosheath
Abstract
We study the magnetic fluctuations at ion scales and down to sub-electron scales (up to 400 Hz) using in-situ Cluster observations. Via spectral statistical analysis we study the anisotropy of turbulence at such small scales and we show that the fluctuations are in agreement with highly oblique kinetic Alfven like fluctuations between ion and electron scales and acoustic like fluctuations at electron scales. Then, we perform case study of burst mode intervals in the solar wind and in the Earth's magnetosheath during the Cluster Guest Investigator campaign in 2015, when C3 and C4 were at 7km apart only. We show that the turbulence at such small scales cannot be described by a mixture of linear waves with random phases, but is strongly intermittent. A detailed study of magnetic fluctuations on C3 and C4 shows signatures of electron-scale magnetic vortices. These observations may suggest that the dissipation at electron scales happens within the coherent structures. Recent MMS measurements provide for the first time measurements of plasma moments with a time resolution high enough to resolve kinetic scales coherent structures. We show our preliminary results on plasma behaviors within the proton scales Alfven vortices.
- Publication:
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Solar Heliospheric and INterplanetary Environment (SHINE 2018)
- Pub Date:
- July 2018
- Bibcode:
- 2018shin.confE..29A