EFDA-JET-PR(04)14

Density Peaking in Low Collisionality ELMy H-mode in JET

Low collisionality, low particle source, ELMy H-modes (type-III) with sawteeth are produced in JET in order to address the question of the density profile evolution in the reference q95 = 3 ITER scenario. By replacing a significant part of the neutral beam heating by RF power the particle flux at mid-radius has been reduced to Γ/ne = 0.17m/s with up to one half being due to the wall neutrals. Density profiles are found modestly peaked in these conditions with a relative density difference of ∆n/〈n〉 = 0.23 across the zone not affected by sawteeth and ELMs. In a region around mid-radius the effective particle diffusivity drops to De,eff ≈ 0.2 χe that could indicate an anomalous pinch. The data are in contrast with the present ITER model that has higher particle diffusivity (De,eff ≈ χe).
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EFDP04014 262.31 Kb