H‐mode by edge ECH in JFT‐2M

H‐mode transition occurred by the edge heating solely by ECH. The launched wave has frequency of 60 GHz and extraordinary mode polarization. The threshold power for the H‐mode transition is as low as 120 kW, which is the least threshold power observed in the JFT‐2M tokamak. The second harmonic ECR layer is located at 0.7–0.9) a (minor radius). The H transition by edge heating occurs not only in the lower‐single‐null divertor configuration but also in the D‐shape limiter configuration. These results show that no additional power in the core plasma region is required to obtain the H‐mode, and that the increase of the peripheral electron temperature is closely related to the trigger of the H‐mode.