Examinations on various scalings for the H-mode edge pedestal width

In this paper, we compare various scalings for the H-mode edge pedestal width proposed so far empirically or based on theoretical or semi-empirical models, and examine possible inter-relations between them. Many of the scalings include poloidal or toroidal Larmor radius, beta-poloidal, normalized Greenwald density and machine size. Some of the scalings include explicitly the local magnetic shear, which is expected to play an essential role in determining the width of the transport barrier through MHD stability and turbulence suppression. Emphasis is placed on the comparison between those scalings without magnetic shear and those with shear. By considering the safety factor dependence of the magnetic shear and its spatial profile, some of the scalings without shear are shown to have a close relation with the scaling including shear.