field's direction. The analysis carried out in Syrovatsky (1971) shows that a zero point is the place of development of a current sheet (see Fig. 4.17.2) in which the current direction coincides with the electric field direction excluding for small sectors at the edges of the cut where the current direction is opposite (the back currents in the region of zero line are generated and maintained not directly owing to the external electric field E but as a result of the plasma motion inhomogeneity caused by this field).

Fig. 4.17.2. The current sheet developing in the place of the zero point. The numerals show the value of the potential A on the corresponding force lines. According to Syrovatsky (1971).

Only in the special case in which the total current may be coordinated with the external field so that the inverse currents will be absent (this may be realized for sufficiently slow motions and at a finite, though high, conductivity of the plasma when the inverse currents are inconsiderable; in this case the width of the sheet is completely determined by the external field, see Fig. 4.17.3).

Fig. 4.17.3. The current sheet developing from the zero point in the absence of the inverse currents. According to Syrovatsky (1971).

In Syrovatsky (1966) the magneto-hydrodynamic equations have been solved for two-dimensional motions of the plasma in the regions where the plasma dynamics is completely determined by magnetic intensities, i.e. the condition

is satisfied and the plasma motion equation turns out to be du

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