Sergey Bogdanov

Experimental study of plasma compression into the sheet in three-dimensional magnetic fields with singular X lines

The formation and evolution of the plasma sheets resulting from the plasma compression in diversified three-dimensional (3D) magnetic configurations with singular X lines are reported on. The research was focused on the correlation between the structure of a plasma sheet and the topology of the initial 3D magnetic configuration, especially on the impact of the guide field aligned with the X line. It has been demonstrated experimentally that plasma compression and formation of extended plasma sheets can take place in configurations with the X lines in the presence of a strong guide field. The electron density distributions in the plasma sheets were found to be rather sensitive to the magnetic field topology. The experiments revealed the effect of progressive decrease of the plasma compression ratio in response to increasing guide field. This effect has two basic manifestations: a decrease of the maximum plasma density and an enlargement of the sheet thickness. Based on the experimental data we advanced a c...

Experimental study of current sheet evolution in magnetic configurations with null-points and X-lines

A review is presented on experimental research of current sheet formation in 3D magnetic configurations containing null-points and/or singular lines of the X-type. Formation of current sheets is revealed to occur in various 3D configurations, both with and without isolated magnetic null-points, specifically in configurations with X-lines. Local characteristics of 3D magnetic configuration define the parameters of the current sheet, which forms usually a twisted surface with an angular orientation determined by a local value of the transverse magnetic field gradient. A degree of plasma compression into the sheet decreases with a rise of longitudinal magnetic field component, displaying a transition to a behavior of uncompressible plasma. It is established that current sheet formation and magnetic reconnection processes can take place within a limited range of initial conditions, while a gradient of transverse magnetic field is the most important parameter.

Modeling of Flare‐type Phenomena in Laboratory Experiments with Current Sheets

In a context of laboratory modeling of astrophysical phenomena, the results are presented on a progress in observations of current sheet formation in a variety of 3D magnetic configurations with some topological singularities. The characteristic features of current sheets are governed by a structure of a 3D configuration, and the sheet can form a twisted surface; its angular orientation is controlled by a local value of the transverse magnetic field gradient. Plasma density inside the sheet decreases in the presence of the longitudinal magnetic field component, displaying the transition to the behaviour of uncompressible plasma. Flare‐type events can be associated with a rapid current sheet disruption when a large amount of magnetic energy is liberated. The principal features of flare phenomena: rapid change in the magnetic field topology, intense plasma heating, generation of plasma flows, and accelerated electrons, have been observed in the course of current sheet disruption in the laboratory conditions.