Effects of supersonic beam and pellet injection on edge electric field and plasma rotation in HL-1M

Abstract

Experimental measurements of edge electric field and plasma rotation have been carried out on both of scrape-off layer (SOL) and the boundary region of HL-1M for Ohmic, Supersonic Beam Injection (SBI) and Multi-shot Pellet Injection (MPI) with a Mach/Langmuir probe array. The radial profiles of the toroidal flow Mach number M, the poloidal flow rotation velocity V pol and the electric field E r are measured during experiments of MPI and SBI respectively. The effects of supersonic beam injection and multi-shot pellet injection on the edge electric field, plasma rotation and fluctuation have been observed. The results show that the change of the radial electric field E r is generated and becomes more negative at the tokamak plasma edge and the sheared poloidal flow relates to the reduction in fluctuation level. During SBI and MPI, poloidal rotation velocities of 3.8 km/s and 10 km/s in the electron diamagnetic direction are measured, respectively. From the measurements we also obtain radial electric fields of −8 and −14 kV/m, respectively in the plasma edge region. It appears that the poloidal velocity is mainly dominated by the E × B drift.