Tungsten Transport and Sources Control in JET ITER-Like Wall H-mode Plasmas

A set of H-mode discharges performed in JET ITER like wall is investigated with respect to control capabilities on tungsten sources and transport. Increasing fuelling by gas puff increases both divertor plasma collisionality and ELM frequency, resulting in a significant decrease of core plasma radiation. Both pedestal flushing by ELMs and divertor screening (including redeposition) are possibly on tasks. For specific scenarios, vertical kicks can be employed to increase the ELM frequency, which results in slightly better situations regarding core pollution by tungsten ions. The application of central ion cyclotron minority heating is efficient to increase the core electron temperature gradient, which results in a significantly lower central impurity peaking. Beryllium evaporation in the main chamber does not reduces the divertor tungsten source, but helps to reduce core radiation by approximately half on approximately 10s of H-mode following it. It suggests that main chamber tungsten sources could dominate the plasma pollution with respect to divertor sources.
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EFDC140131 1015.73 Kb