Heavy Element Spectoscopy and Models

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.

Workpackage WP1:Heavy element baseline generation

Enable user production of a baseline set of atomic data for any element tuned to user's own application. Supply a standard baseline for set of heavy elements for archiving and release in the ADAS database.

Workpackage WP2: Managing spectral complexity

Enable creation of massive line sets for arbitrary heavy element ions, with separation into strong individual lines emissivities and feature emissivities defined on a spectrometer range. Embedding of these capabilities in the experimental programmes at Euratom Associated Laboratories. Such embedding is a central objective of the ADAS-EU proposals and the preparations for ITER.

Workpackage WP3: Fitting to impurity transport codes

Enable superstage compression for 2-D/3-D transport codes, delivering standard baseline collisional-radiative coefficients (adf11) augmented with ZCD, YCD, ECD, with various partitioning strategies. Embedding of these capabilities in the modelling application programmes at Euratom Associated Laboratories. Such embedding is a central objective of the ADAS-EU proposals and the preparations for ITER.

Workpackage WP4: Lifting the baseline

Enable user production of a level 1 set of explicit configuration average direct ionisation and excitation/auto-ionisation collisional rate data with Auger branching for complex ions. Enable user production of level 1 explicit state selective dielectronic recombination in the Burgess-Bethe General Program (BBGP) approximation for complex ions. Implement advanced parametric form adjustment for all ions of all elements using explicit data above to lift the baseline. Supply a revised baseline for a set of heavy elements for archiving and release in the ADAS database.

Workpackage WP5: Embedding low and high ion fiducials

The complexity of many-electron heavy element ions is at its most severe for neutral and near neutral atoms with increasing imprecision of baseline and level 1 modelling. Sound theoretical photon efficiencies for tungsten are elusive. Also such ions are typically in a highly ionising environment in fusion with pathways for multiple electron loss which are discounted for lighter elements. At the other, highly ionised, end of the scale, full relativistic collision calculations become appropriate. Sub-contracting to European university specialists for delivery of fiducial calculations to ADAS-EU specification will enable correction of this situation and take the ADAS-EU capability from level 1 to level 2 for named key ions.