Impurity behaviour during ICRF heating in JFT-2M

Abstract The impurity behaviour during the ICRF heating phase was studied in the JFT-2M tokamak. In this experiment, impurity behaviour during the ICRF heating phase was studied with special attention to the boundary electron temperature. From these experimental results, it was concluded that carbon (limiter material) impurity was released by an ion sputtering accelerated by the sheath potential. Metal impurities such as iron and titanium released from the antenna and/or near the antenna region are caused by some additional mechanism by applying the RF during the ICRF heating phase.