Inverse currents in current sheets in the Earth magnetosphere and in laboratory experiment

We discuss the possibility of comparing the data of satellite observations and the laboratory experiment on the study of deceleration of plasma jets propagating in the current sheets. Satellite observations show that plasma flows propagating in the magnetotail toward the Earth consist of individual plasma jets with scales of several thousand km and a duration of 10–5 sec. When propagating across a strong dipole field in the near magnetosphere, plasma jets are decelerated and destroyed. These processes are apparently associated with the formation of a system of inverse currents at the leading front of plasma jets.

On the basis of experimental data obtained with the CS-3D setup (GPI RAS), we analyze the processes of acceleration and deceleration of superthermal plasma flows that move along the surface of the current sheet. Particular attention is drawn to the fact that accelerated plasma flows are limited both in time and in length. We demonstrate that short durations of the flows are due to excitation of inverse currents at the side edges of the sheet, as follows from the analysis of the evolution of magnetic fields, currents, Ampère forces, and the energy of plasma jets. It should be emphasized that the inverse currents arise as a result of introducing fast plasma flows into a strong transverse magnetic field at the side edges of the sheet. The inverse currents are associated with the Ampere forces, which cause deceleration of previously accelerated plasma flows, and the work done by these braking forces results in a significant decrease in the energy of plasma jets.

Artemyev A.V., **Frank A.G.

*EPSS/UCLA, CA, USA, aartemyev@igpp.ucla.edu

**Prokhorov General Physics Institute of the Russian Academy of Sciences, Moscow, Russia, annfrank@fpl.gpi.ru