Cold-dense plasma sheet and hot-dense ions in the inner-magnetosphere Original Research Article

Cold-dense plasma sheet (CDPS) is known to appear during extended northward IMF periods. Its appearance suggests enhanced entry of the solar wind into the magnetosphere during the times when it is supposed to be most closed, in a manner totally different from active times, and that on to closed field lines. To understand the CDPS formation mechanism, which still remains open, anatomy of CDPS is performed in this study. By inspecting the ion spectrum characteristics CDPS is classified into three categories. Dawn-dusk asymmetry is revealed as the spatial distributions of the three categories are plotted separately, which indicates that different heating/transport processes are operative on different sides of the magnetotail. On dawnside a group of data characterized by the highest temperature from one of the CDPS categories is distributed at the plasma sheet inner-edge and is connected to the hot-dense ions (HDIs) at the further inner region. An independent analysis indicates that HDIs not associated with elevated solar wind dynamic pressure appear in the dawnside inner-magnetosphere during extended northward IMF. Both studies points to the idea that HDIs are the inner-magnetosphere extension of dawnside CDPS and that there is significant dawn-dusk asymmetry in heating and transport in the magnetotail under northward IMF.