U.S. Department of EnergyOffice of Scientific and Technical Information
The updated ITPA global H-mode confinement database: description and analysis
Abstract
The multi-machine ITPA Global H-mode Confinement Database has been upgraded with new data from JET with the ITER-like wall and ASDEX Upgrade with the full tungsten wall. This paper describes the new database and presents results of regression analysis to estimate the global energy confinement scaling in H-mode plasmas using a standard power law. Various subsets of the database are considered, focusing on type of wall and divertor materials, confinement regime (all H-modes, ELMy H or ELM-free) and ITER-like constraints. Apart from ordinary least squares, two other, robust regression techniques are applied, which take into account uncertainty on all variables. Regression on data from individual devices shows that, generally, the confinement dependence on density and the power degradation are weakest in the fully metallic devices. Using the multi-machine scalings, predictions are made of the confinement time in a standard ELMy H-mode scenario in ITER. The uncertainty on the scaling parameters is discussed with a view to practically useful error bars on the parameters and predictions. One of the derived scalings for ELMy H-modes on an ITER-like subset is studied in particular and compared to the IPB98(y,2) confinement scaling in engineering and dimensionless form. Transformation of this new scaling from engineeringmore »
- Authors:
- Publication Date:
- DOE Contract Number:
- AC02-09CH11466
- Research Org.:
- Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
- Sponsoring Org.:
- USDOE Office of Science (SC)
- Keywords:
- H-Mode; Database; ITER
- OSTI Identifier:
- 1814950
- DOI:
- https://doi.org/10.11578/1814950
Citation Formats
Verdoolaege, G, Kaye, S M, Angioni, C, Kardaunn, O W J F, Maslov, M, Romanelli, M, Ryter, F, and Thomsen, K. The updated ITPA global H-mode confinement database: description and analysis. United States: N. p., 2021.
Web. doi:10.11578/1814950.
Verdoolaege, G, Kaye, S M, Angioni, C, Kardaunn, O W J F, Maslov, M, Romanelli, M, Ryter, F, & Thomsen, K. The updated ITPA global H-mode confinement database: description and analysis. United States. doi:https://doi.org/10.11578/1814950
Verdoolaege, G, Kaye, S M, Angioni, C, Kardaunn, O W J F, Maslov, M, Romanelli, M, Ryter, F, and Thomsen, K. 2021.
"The updated ITPA global H-mode confinement database: description and analysis". United States. doi:https://doi.org/10.11578/1814950. https://www.osti.gov/servlets/purl/1814950. Pub date:Mon Mar 01 00:00:00 EST 2021
@article{osti_1814950,
title = {The updated ITPA global H-mode confinement database: description and analysis},
author = {Verdoolaege, G and Kaye, S M and Angioni, C and Kardaunn, O W J F and Maslov, M and Romanelli, M and Ryter, F and Thomsen, K},
abstractNote = {The multi-machine ITPA Global H-mode Confinement Database has been upgraded with new data from JET with the ITER-like wall and ASDEX Upgrade with the full tungsten wall. This paper describes the new database and presents results of regression analysis to estimate the global energy confinement scaling in H-mode plasmas using a standard power law. Various subsets of the database are considered, focusing on type of wall and divertor materials, confinement regime (all H-modes, ELMy H or ELM-free) and ITER-like constraints. Apart from ordinary least squares, two other, robust regression techniques are applied, which take into account uncertainty on all variables. Regression on data from individual devices shows that, generally, the confinement dependence on density and the power degradation are weakest in the fully metallic devices. Using the multi-machine scalings, predictions are made of the confinement time in a standard ELMy H-mode scenario in ITER. The uncertainty on the scaling parameters is discussed with a view to practically useful error bars on the parameters and predictions. One of the derived scalings for ELMy H-modes on an ITER-like subset is studied in particular and compared to the IPB98(y,2) confinement scaling in engineering and dimensionless form. Transformation of this new scaling from engineering variables to dimensionless quantities is shown to result in large error bars on the dimensionless scaling. Regression analysis in the space of dimensionless variables is therefore proposed as an alternative, yielding acceptable estimates for the dimensionless scaling. The new scaling, which is dimensionally correct within the uncertainties, suggests that some dependencies of confinement in the multi- machine database can be reconciled with parameter scans in individual devices. This includes vanishingly small dependence of confinement on line-averaged density and normalized plasma pressure (β), as well as a noticeable, positive dependence on effective atomic mass and plasma triangularity. Extrapolation of this scaling to ITER yields a somewhat lower confinement time compared to the IPB98(y, 2) prediction, possibly related to the considerably weaker dependence on major radius in the new scaling (slightly above linear). Further studies are needed to compare more flexible regression models with the power law used here. In addition, data from more devices concerning possible ‘hidden variables’ could help to determine their influence on confinement, while adding data in sparsely populated areas of the parameter space may contribute to further disentangling some of the global confinement dependencies in tokamak plasmas.},
doi = {10.11578/1814950},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Mar 01 00:00:00 EST 2021},
month = {Mon Mar 01 00:00:00 EST 2021}
}