Tungsten accumulation during ion cyclotron resonance heating operation on WEST

The observation of radiative collapses during ion cyclotron resonance heating (ICRH) operation on the full tungsten WEST tokamak constitutes a unique opportunity to get a quantitative balance of the sources and sinks in the core region of the plasma. Experimental analysis and numerical modelling evidence a significant reduction of the effective electron heat source delivered by ICRH compared with expectations on the one hand, and a complex interplay of mechanisms acting on the collisional peaking of tungsten on the other hand. Besides providing an explanation for the observed radiative collapses, this work outlines the variety of phenomenon determining the tungsten profile in ICRH operation.