Simulation of JET ITER-Like Wall pulses at high neon seeding rate

A series of neon seeded JET ELMy H-mode pulses is considered from the modeling as well as from the experimental point of view. For two different Ne seeding rates and two different D puffing gas levels the heating power, Pheat, is in the range 22–29.5 MW. The main focus is on the numerical reconstruction of the total radiated power (which mostly depends on the W concentration) and its distribution between core and divertor and of Zeff (which mostly depends on the Ne concentration). To model with the self-consistent code COREDIV the core and the SOL two input parameters had to be adjusted case by case: the SOL diffusivity, DSOL, and the core impurity inward pinch, vpinch. DSOL had to be increased with increasing ΓNe and the level of vpinch had to be increased with decreasing the ELM frequency, fELM. Since for any given gas puffing level fELM decreases with the Ne seeding rate, this might lead to a limitation in the viability of reducing the target heat load by Ne seeding at moderate ΓD, while keeping acceptably low Zeff. In the considered range of temperatures and densities of the SOL, the numerical results suggest the balance between friction and thermal forces to be in favor of the frictional drag for tungsten, thus providing a W screening effect.