Comparison of edge pedestal parameters for JT-60U and DIII-D H-mode plasmas

Edge pedestal parameters (pedestal temperature and density, pedestal width) for JT-60U and DIII-D are studied and compared. For the discharges used in the study, the JT-60U H-mode operation space is in the high edge ion temperature and low edge electron density region, whereas DIII-D discharges have higher edge electron density and lower electron temperature. The pedestal width scaling has been studied separately in each machine. We tested these pedestal scalings against each other using JT-60U ion temperature pedestal width data and DIII-D electron temperature pedestal width data. Three previous scalings for pedestal width (Δ∝ε 0.5 ρ pi , Δ/ R ∝(ρ pi / R ) 0.66 , Δ/ R ∝(β p PED ) 0.4 ) are tested using temperature pedestal widths from both machines. The relations between pedestal width and dimensionless parameters are examined. We propose a new pedestal width scaling for T e and T i based on this study of the two machines. The new scaling includes normalized poloidal gyroradius and Greenwald density: Δ∝ a ρ * 0.4 n G * 0.3 κ -1.5 . The result of the comparison of these scalings is that the new scaling and Δ/ R ∝(β p PED ) 0.4 are well fitted and the fitting errors are almost the same as experimental error. However, further study is necessary for scaling parameters.