2016 Volume 11 Pages 2401052
Hall effect on counter-helicity spheromak merging is experimentally investigated in a low-S∗ region, where S∗ is the ratio of plasma minor radius to ion skin depth. Direct measurement of magnetic field, ion flow, electron density revealed that Hall effect affect not only merging reconnection phase but also relaxation phase through formation of ion flow and current density profiles. Hall effect breaks the symmetry of the “case-O” and “case-I” counter-helicity spheromak merging, which are defined by combinations of poloidal flux and toroidal flux of initial spheromaks. Formation of toroidal current profile and radial outflow pattern are different in case-O and case-I during merging process, and that results in great difference of profiles of electron density after merging.
