Thin current sheets observed by MAVEN in the Martian magnetotail
Abstract
By using MAVEN observations we investigate the structure of cross-tail current sheet (CS) in the Martian magnetotail. The CSs play a crucial role in the conversion of magnetic energy into kinetic and thermal energy of plasma particles via magnetic reconnection. Signatures of magnetic reconnection were reported in the Martian magnetotail, but the mechanisms leading to reconnection onset are still unknown. Previous observations in the Earth magnetotail showed that the stretching of the CS magnetic configuration leads to formation of thin CS embedded into a thicker one. Such multiscale configuration can be a source of free energy for excitation of plasma instabilities capable to generate X-type and/or O-type magnetic configuration and trigger reconnection. By using high-resolution magnetic field data we reported the formation of multiscale CS structure in the Martian magnetotail with the inner super thin current sheet (STCS) having a half-thickness L ~ 5 km or less, which is much less than the gyroradius of thermal protons (ρP) . The STCSs are embedded into a thicker sheet with L ≥ ρP forming a multiscale electric current configuration. Our statistical analysis showed that the formation of STCS does not depend on ion composition, but it is controlled by the small value of the normal component of the magnetic field at the neutral plane of the sheet. A number of the observed multiscale CSs are located in the parametric map close to the ion tearing-unstable domain. Thus, the CS thinning and the formation of STCS can lead to a new metastable equilibrium, in which the CS undergoes topological changes enabling the process of fast magnetic reconnection.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFMSM42B..05G
- Keywords:
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- 2740 Magnetospheric configuration and dynamics;
- MAGNETOSPHERIC PHYSICS;
- 2756 Planetary magnetospheres;
- MAGNETOSPHERIC PHYSICS;
- 5435 Ionospheres;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 5443 Magnetospheres;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS