Magnetic Structure of the Current Sheets Formed in Magnetic Fields with Singular Line of X- Type.

Bogdanov S., Bugrov S., Frank A., Markov V.

The process of current sheet formation in various magnetic configurations 
with a singular line of X-type was investigated experimentally. Three magnetic 
field components were measured by a set of small probes which were moved 
in the plasmas volume. The distribution of the electric current and its 
time evolution were calculated from these data. 
It was found that the current distribution obtained the typical shape of a 
sheet both in the 2D and in the 3D magnetic configurations. At the same time 
the guide field Bz may have a pronounced effect on the current sheet 
properties. The current density decreases and the sheet thickness increases 
with the guide field increasing. The similar influence of the guide field 
on the plasma density distribution was observed earlier: degree of plasma 
compression into the sheet decreased with increasing the guide field.
The measurements of the excessive Bz field demonstrated its increase in the 
current sheet as compared with the initial value of the guide field. The 
additional pressure due to the excessive Bz resulted in lower plasma and 
current compression into the sheet.