Steps towards an integrated data analysis Basic concepts and

Aspects of the integration of different data sources are discussed with respect to improvement of reliability and significance of experimental results. Thomson scattering data have been analysed by means of Bayesian probability theory. This much improved s

29th EPS Conference on Plasma Phys. and Contr. Fusion Montreux, 17-21 June 2002 ECA Vol. 26B, P-5.103 (2002)

Steps towards an integrated data analysis: Basic concepts and Bayesian analysis of Thomson scattering data A. Dinklage1, R. Fischer2, G. Kühner3, H. Maaßberg1, E. Pasch33

1Max-Planck-Institut für Plasmaphysik, TI Greifswald, EURATOM Association,

Wendelsteinstr.1, 17491 Greifswald, Germany 2Centre for Interdisciplinary Plasma Science, Boltzmannstr. 2, 85748 Garching, Germany 3Max-Planck-Institut für Plasmaphysik, EURATOM Association, Boltzmannstr. 2,

85748 Garching, Germany

Abstract

Aspects of the integration of different data sources are discussed with respect to improvement of

reliability and significance of experimental results. Thomson scattering data have been analysed by means of Bayesian probability theory. This much improved statistical model for the evaluation of

the data can be used for assessment and improvement of the diagnostics. A Bayesian graphical

model has been developed for the linkage of different diagnostics, with the goal of arriving at a

fully integrated data analysis.

Background

Consistency checks and validation of experimental data from different diagnostic sources is a persistent problem in magnetically confined plasma research. If compared to efforts in

diagnostic hardware development, data analysis turns out to be frequently a sideline

activity, in particular if the analysis has to combine information from different sources.

Therefore, the goal of our investigation is to explore possibilities for integration of

available physics information in order to enhance the significance and the reliability of

experimental data from fusion devices. The notion of integrated data analysis has to be

understood not only as a sophisticated combination of available data by statistical means,

but also as the usage of expert knowledge of all parties involved in the data validation

process and to integrate theoretical considerations and modelling. In order to provide

platforms for communication and to minimize efforts in data administration, computer

science becomes an essential part of the integration concept. Many of the positive aspects

emerging from a well organized data management have been proven on large scale devices like JET [1].

A great problem for integration of the analysis of fusion data comes from the extreme

heterogeneity of the information sources. E.g., one has to deal with many different

diagnostics on different spatial and time scales as wells as theoretical considerations, like

equilibrium calculations or transport modelling. Our investigations start with a rigorous

error analysis of data (here Thomson scattering (TS) data for the electron density ne and the electron temperature Te), which will later be combined with other measurements (e.g.

spatial profiles of ne and Te on flux coordinates from TS, ECE and lithium beam