Observation of edge fluctuation characteristics on the HL-2A tokamak

The edge plasma fluctuation characteristics are studied by the reciprocating fast scanning 6-probes in the boundary region of the HL-2A tokamak. The probes can be applied to measure, simultaneously, the temporal and spatial profiles of the edge plasma parameters, the relationship of Reynolds stress with the poloidal flow and the zonal flows, the changes of radial particle flux and radial heat flow in one discharge. These parameters are used to analyze edge turbulence and coherency under the condition of multi-pellet injection (MPI) and supersonic molecular beam injection (SMBI). The results suggest that SMBI and MPI can influence the edge fluctuation characteristics, the radial gradient of Reynolds stress is able to drive zonal flows, as well as the turbulence and the transport may be suppressed. (authors)