Transport and multiple charge state CXS

(part of theme Charge Exchange Spectroscopy)

Objective

For elements of nuclear charge >~18, the charge exchange receivers may not be the bare nucleus over significant regions of the plasma. Simultaneous multi-chord CXS observations of lines from adjacent stages are localised along the beam line and the inferred radial distributions reflect impurity transport directly. Support of this scenario requires a CXS receiver population modelling adjusted for a non-empty ion core and predictive modelling of local emission along a beam pencil with receiver ionisation stage fractional abundances from a transport model. A novel cross-validation experiment type targeting transport parameters and consistency of passive emission along lines of sight may be possible by alternating between active and passive observations while stepping up through heavier species. The present tasks will enable these types of analysis. 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.

Specific tasks

• Enable adjustment of l-mixing/cascade models for CXS emission by medium weight partially stripped species through improved level energy separations from static polarisabilities.
• Enable generation of all charge exchange emission functions of adjacent partially stripped ions of an element along a beam-line pencil from a UTC/SANCO radial transport scenario.
• Establish bootstrap paths through medium/heavy element sets and ion groups and between active CXS and passive line of sight observations. Assemble appropriate emission predictions for analysis.
• Experimental exploitation/validation. Timing is subject to experimental campaigns and indeterminate at this stage.
• Revision. Timing is subject to laboratory responses and indeterminate at this stage.