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 DIU-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 temper ature and low edge electron density region, whereas DIII-D discharges have higher edge electron density and lower electron temperature. The pedestal w idth scaling has been studied separately in each machine. We tested these p edestal scalings against each other using JT-60U ion temperature pedestal w idth data and DIII-D electron temperature pedestal width data. Three previo us scalings for pedestal width (Delta proportional to epsilon(0.5)rho(pi), Delta/R proportional to (rho(pi)/R)(0.66), Delta/R proportional to (beta(p) (PED))(0.4)) are tested using temperature pedestal widths from both machine s. The relations between pedestal width and dimensionless parameters are ex amined. We propose a new pedestal width scaling for T-e and T-i based on th is study of the two machines. The new scaling includes normalized poloidal gyroradius and Greenwald density: Delta proportional to a rho*(0.4)n(G)*(0. 3)kappa(-1.5). The result of the comparison of these scalings is that the n ew scaling and Delta/R proportional to (beta(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.