Speaker
Description
The WEST tokamak has been used to study long-pulse scenarios in a full Tungsten environment. Its contamination in the core, which reduces performance, as well as the location of erosion/deposition sites are important. It continues to be difficult however, to get accurate estimates of sputtered fluxes and Tungsten content in any given pulse. Modelling that aims to answer this question should ideally be integrated, both in terms of core-edge as well as main ion-impurity.
To this end, the SOLEDGE-3X code was recently extended in order to enable it to perform core-edge integrated simulations of all relevant species. The plasma wall interaction includes the sputtering and prompt redeposition of Tungsten using analytical models that capture high-energy tail sputtering as well as the sputtered energy distribution. The edge-SOL transport is modelled in 2D, using anomalous diffusivities. In the core meanwhile, a 1D model is used, coupled to QLKNN-10D, a fast turbulence model for transport, as well as an analytical neoclassical model for the transport of Tungsten. Using this framework, a number of applications have been shown.
A comparison was made with the long pulse scenario WEST #58245. The flat-top averaged core density and temperature profiles were reproduced using the integrated framework, as well as the density at the strike points measured using Langmuir probes. Oxygen was used as a proxy impurity, with the source being from the wall as opposed to from the inner boundary as in previous work. The radiated fraction of Tungsten was then looked at and found to be in the experimentally measured flat-top range. The lower strike points and baffle were the main contributors in terms of sputtering sources, with the baffle found to be less effectively screened. Comparisons are being done to bolometry and visible spectroscopy at the strike points. Further applications of the model are ongoing, in particular with respect to a study of the sensitivity of the input power to the radiated fraction.
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