closed magnetic flux (the reason why it is rather small shall be discussed later). The other is in the middle latitudes extending along the field lines. This elongated corotation region separates the OG regions with out-going current from the PC regions with in-going current. In other words, the middle-latitude corotation region is formed where the directions of the currents change. Let us call this region “the current-neutral zone”. In our numerical experiment, there is no significant flow of both positive and negative particles along the magnetic field lines in the current-neutral zone. The cloud of negative particles is naturally formed there. The current-neutral zone is formed in both the dipole and modified magnetic field cases, although the locations were slightly different because it is formed along the magnetic field lines.

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The traditional dead zone is defined by the magnetic field lines closed within the light cylinder, but the one in our simulation does not reach the light cylinder, and is obviously small. Additionally, the shape of the disk does not follow the magnetic field lines. As shown in figure \[fig:res02\], the inner part of the disk corotates with the star, but on the other hand the super-rotation, which is 