ADAS-EU Scientific Themes
Heavy element behaviour in fusion plasma is a central issue for ITER, an issue being addressed by current experiments and modelling across Europe. Atomic physics has essential tasks in these developments - to allow interpretation of observed spectral emission and to represent adequately the ionization state of such very complex species and their ions. The path to achieving successful support by ADAS-EU depends on careful problem regulation, layered levels of precision and a focus on the highest levels of refinement only where is it necessary. The work packages of this theme, specified in more detail below, are the systematic delivery of a comprehensive solution. It will make use of novel concepts such as superstages, feature emissivities, partitions etc. and will include specially commissioned calculations/measurements which will secure the precision of the atomic data and atomic models.
Improved precision in light element, with silicon as an example.
Quantitative charge exchange spectroscopy is a key diagnostic tool at most fusion laboratories and will be at ITER, where a diagnostic neutral beam is planned. The scope of such analysis continues to expand with a move to heavier elements, especially argon, in progress. Such heavier elements, which may be partially ionized over core regions of the fusion plasma, link active charge exchange emission shell localization and transport. ADAS-EU will enable and support such developments. The work packages of this theme will support hydrogen, helium and lithium beam diagnostic models/ analysis and will extend the fundamental databases for the new species and new energy ranges. The provision and support will include both spectral fitting and spectral analysis packages. Specially commissioned studies will again secure the precision of the atomic data and atomic models.
The neutral beam emission support by ADAS-EU will reflect a return to direct diagnostic interpretation of beam emission intensities, that is, the motional Stark multiplets of hydrogen isotope beams. A lithium beam emission edge diagnostic with its accompanying atomic databases will also be consolidated and supported. The heavier species extension of the first and second theme will be followed in this theme too, in the context of beam stopping and beam excitation. The work packages will support and ensure a consistent integrated picture of high resolution beam emission and beam stopping. Special studies of directional collisions in the Stark manifold picture will target and enhance precision.
The theme is concerned with spectroscopy of line groups, called special features, which because of their plasma parameter dependencies have special diagnostic impact. ADAS-EU will support existing special features, such as Zeeman/Paschen-Back split multiplets, characteristic He-like/Li-like soft X-ray resonance / satellite line spectral intervals, spectral series and limits. It will also extend the range of special features available to the analyst. Other work packages will deliver a unifying vehicle for exploiting such features in optimized spectral fitting as well as for providing pedagogical support. The work packages will provide very high precision and comprehensive coverage.
The theme will extend ADAS-EU support into the observable diatomic part of fusion spectra and the associated diatomic population modelling. The work packages emphasis the consolidation and support of H2 vibronic population models and their links to H population models and emission. ADAS-EU will bring special expertise to bear on the underlying molecular databases for such systems. It will deliver analysis methodology and support spectral fitting /analysis at the highest precision levels.