Effects of RF injection on MHD in ICRF heating experiments on the HL-1M tokamak

Effects of RF injection on the behavior of MHD in ICRF experiments on the HL-1M tokamak are presented. The effects can be studied by analysis of soft X-ray. It is observed that the RF injection causes sawtooth. It is also observed that the RF injection can suppress the sawtooth on soft X-ray. Moreover, the improvement of plasma confinement is observed in ICRF experiment. In a discharge of improved confinement, the edge signals of Dα is decreased while the electron density of plasma center is increased. The data calculation based on the signals of Mach probes shows that the electric field of plasma surface and poloidal flow rotation velocity are obviously influenced by the RF injection