The updated ITPA global H-mode confinement database: description and analysis

Abstract The multi-machine International Tokamak Physics Activity (ITPA) Global H-mode Confinement Database has been upgraded with new data from JET the ITER-like wall and ASDEX Upgrade full tungsten wall. This paper describes database presents results of regression analysis to estimate global energy confinement scaling in plasmas using a standard power law. Various subsets are considered, focusing on type divertor materials, regime (all H-modes, ELMy H or ELM-free) constraints. Apart ordinary least squares (OLS), two other, robust techniques applied, which take into account uncertainty all variables. Regression individual devices shows that, generally, dependence density degradation weakest fully metallic devices. Using scalings, predictions made time scenario ITER. parameters is discussed view practically useful error bars predictions. One derived scalings for H-modes an subset studied particular compared IPB98(y, 2) engineering dimensionless form. Transformation this variables quantities shown result large scaling. space therefore proposed as alternative, yielding acceptable estimates scaling, dimensionally correct within uncertainties, suggests that some dependencies can be reconciled parameter scans includes vanishingly small line-averaged normalized plasma pressure ( ? ), well noticeable, positive effective atomic mass triangularity. Extrapolation ITER yields somewhat lower prediction, possibly related considerably weaker major radius (slightly above linear). Further studies needed compare more flexible models law used here. In addition, concerning possible ‘hidden variables’ could help determine their influence confinement, while adding sparsely populated areas may contribute further disentangling tokamak plasmas.