Parameter dependence of density pedestal width and correlation with pedestal turbulence in EAST type-I ELMy H-mode plasma

The density pedestal structures in a series of type-I ELMy H-mode discharges (0.6 MA/2.5 T) with upper single null (USN) divertor configuration have been studied in EAST. To obtain the pedestal width, density profiles are fitted via the modified hyperbolic tangent (mtanh) function and the two-line method. The pedestal widths from these two methods have a similar tendency. Significant impacts of pedestal poloidal beta and pedestal collisionality on the density pedestal width have been observed for the first time in EAST. The non-linear regressions suggest the density width scaling in type-I ELMy EAST plasma are wne∝c(νped⁎)0.27−0.33⋅(βp,ped)0.5−0.58. The density fluctuations in the bottom of the pedestal from the fluctuation reflectometry imply an enhanced density fluctuation (Pfluc) and an obvious spectral broadening in the high collisionality regime of νped⁎≥3. The experimental results suggest that the pedestal turbulence would play an important role in the evolution of the pedestal structure.