Structure of current sheets in the sector boundaries: Helios 2 observations during early 1976

We examined the orientation and structure of 14 current sheets that were observed in sector boundary regions during the primary mission of Helios 2 (January through April 1976). We found that the field rotation through the current sheets (which are not null sheets) tends to occur at large angles with respect to the ecliptic plane. Most of the observed structures (which had typical thickness ranging between 1 × 10 4 and 6 × 10 4 km) can be interpreted as tangential discontinuities oriented at large angles with respect to the ecliptic plane. We also discuss the implications of a comparison between present results and the global configuration of the sector boundary surface. In particular, if we assume that the sheet normals are the same as the local normals to the global surface, our results do not support any solar cycle modulation for the orientation of boundaries.