Hall Effect in Laboratory and Space Current Sheets
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The role of the Hall effect in the formation of thin current sheets (CSs) is analyzed by comparing results of laboratory and satellite experiments. In spite of the strong difference in the plasma parameters, both laboratory and space CSs are characterized by the hot ion component and cold isotropic electron component. Such a relation between the ion and electron components would have to guarantee the predominant contribution of the ion diamagnetic drift current to the total current density. However, the Cluster spacecraft observations of thin CSs in the Earth’s magnetotail have revealed the predominance of a strong electron (rather than ion) current. This may be due to the Hall effect, which causes generation of electric fields, which redistribute the CS currents in favor of the electron currents at the expense of the ion currents. Observations demonstrate that the thinner the CS, the stronger this effect. A similar tendency was also observed in laboratory experiments on CS formation in plasma with ions of different mass, which made it possible to vary the CS relative thickness and monitor the consequences of the Hall effect. Comparison of results of satellite and laboratory experiments indicates that the Hall effect plays an important role in the formation of thin CSs in both magnetospheric and laboratory plasmas.
This work was performed in the framework of the Program “Fundamental Problems of Dynamics, Confinement, and Heating of Plasma in Three-Dimensional Magnetic Configurations” (State Contract no. 0024-2018-0045). This work was also supported in part by the Department of Physical Sciences of the Russian Academy of Sciences under the Fundamental Research Program no. III.2 “Dynamics of Rarefied Plasma in Space and Laboratory” and the Russian Foundation for Basic Research (project no. 15-02-03644). The work by R. Nakamura was supported by the Austrian Science Fund (project no. FWF I2016-N20).
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