Development of a two-term model for the confinement in ELMy H-modes using the global confinement and pedestal databases

The overlap of pulses in the pedestal database and the global H-mode confinement database has been increased. This has resulted in a new improved combined dataset with core and pedestal energy data. Regression analysis of this dataset indicates that in ELMy H-mode the pedestal energy scales differently from the core energy and degrades strongly with plasma pressure β. Using these regression results to estimate the pedestal energy in the full ELMy dataset of the global H-mode confinement database, a new two-term scaling for ELMy H-mode confinement has been found that indicates that the core confinement scales as a pure gyro-Bohm scaling with no β degradation. At present, these findings are not conclusive as the dataset is limited in the range of data and has strong correlations between the plasma parameters.