1ITER Joint Central Team, Joint Work Site, D-85748 Garching, Germany2 JAERI, Naka Fusion Research Establishment, Ibaraki-ken, 311-01 Japan3 JET Joint Undertaking, Abingdon Oxon., OX14 3EA, UK4 Plasma Fusion Centre, MIT, Cambridge, MA 01239, USA5 General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 USA6 Max-Planck-Institut fur Plasmaphysik, EURATOM Assoc., D-85748 Garching, Germany1. IntroductionEnergy confinement during H-mode in Tokamaks strongly depends on the temperature atthe top of the H-mode pedestal [1]. This pedestal temperature is determined by the gradient andthe width of the pedestal edge. In the case of the Type-I ELMy regime, which is assumed forpulsed operation in ITER, it is widely observed that the pressure gradient is close to the idealballooning stability limit. Thus, the discharge parameter and machine size dependence of thepedestal width is of primary importance for predicting the pedestal temperature in ITER. The ITER multi-machine pedestal database activity has been started to identify the overallfeatures of the pedestal region for the various discharge modes including the LH transition, TypeI and Type III ELMs, the ELM-free and EDA (Enhanced Dα) phases. For these regimes, thepedestal data (mainly scalar data and limited data for profiles from some machines) from majordivertor Tokamaks, ASDEX-U(AUG), C-MOD, DIII-D, JET and JT-60U, are archived in thedatabase. Although the data archive is still on-going, this paper presents an initial study on thepedestal width/height during the ELM-free, EDA and Type I ELMy phases based on thepresently available data.So far, the width studies have been limited to one machine [2-6] or at most to a comparisonbetween two machines (C-MOD and DIII-D [7]). Studies show, however, that the parameterdependence of the pedestal width is rather different from machine to machine, e.g., somemachines observe ion poloidal Larmor radius dependence when considering thermal or fast ions[8, 9], while such dependence is not observed in some machines [6]. Universal scaling is stilldifficult to derive. Another limitation of the database is that direct comparison of the width is notpossible in many machines due to diagnostic limitations. Thus, in this paper, we mainly examinethe pedestal pressure in terms of several candidate width scalings such as poloidal Larmor radiusand other theoretical models assuming that the pressure gradient is determined by the idealballooning stability limit.We will also propose one possible interpretation of the divergent observations of the widthbased on turbulence suppression by a combination of the electric and magnetic field shear.Some examinations on this interpretation on the database are also presented.2. Examination on pedestal heightSeveral machines observe the ion poloidal Larmor radius dependence for the pedestalwidth and a majority of the machines observe the critical pressure gradient which is close to theideal ballooning limit. Thus, as an initial choice of the scaling parameters for the pedestal height,we will employ (dp/dr)