Formation of two-dimensional current sheets under high initial pressure conditions

The possibilities of current-sheet formation in two-dimensional magnetic fields with a null line as well as the characteristic features of the plasma dynamics under high initial pressure conditions (helium, P(0)approximate to 300 mtorr) are investigated for the first time. It is shown that current-sheet formation and efficient compression of the plasma into a sheet require that the magnetic field gradient be sufficiently large. A brightly emitting compact region with electron density N(e)similar to 9 X 10(16) cm(-3), an order of magnitude higher than the gas atom density, was observed to format the center of the layer. (C) 1998 American Institute of Physics. [S1063-7761(98)00510-1].