Effect of rotating helical magnetic field on the turbulence fractal structure and transport in the tokamak edge plasma

Fractal structure of the edge turbulence and enhanced turbulent transport have been studied in the tokamak HYBTOK-II with a variation of the rotating helical magnetic field (RHF) frequency in the range 5–30 kHz. Edge fluctuations have non-Gaussian statistics caused by intermittent bursts with a time scale of 40–100 µs. The variation in the RHF frequency has a selective effect on the fractal structure of edge turbulence and the turbulent flux, demonstrating a selective control of the transport process. A delayed synchronization control of resonant drift wave modes by the RHF is considered as a candidate mechanism to explain the dependence of the effect on the RHF frequency.