Calculation of observable quantities using a divertor impurity interpretive code, DIVIMP

Abstract

Our picture of divertor edge plasma behaviour is largely theoretical with little experimental confirmation. Questions exist with regard to impurity production mechanisms, sputtering yields, plasma ion temperatures, parallel temperature gradients, the existence of plasma flow reversal, cross-field diffusion coefficients, etc. Spatial distributions of impurity ions of successive charge states in the edge, when interpreted with an impurity production/transport code, provide a basis for discriminating amongst the various theoretical possibilities. In this paper, for an example case, a wide range of models/assumptions about the divertor edge plasma behaviour is examined with regard to the effect on the spectroscopic intensities of C+ through C5+ in the vicinity of the divertor targets. It is shown that a single spectroscopic viewing location can be sufficient to discriminate amongst most of the models/assumptions made about the divertor plasma behaviour. More refined discrimination would require additional viewing locations and diagnostics, such as Doppler temperature measurements.