TF ripple effects on the NBI deuteron confinement in JET

• Ripple induced reduction of the fluxes of deuterium neutrals in the 5-40 keV energy range from the plasma mid-plane was observed in recent JET experiments. The maximum observed reduction of D0 fluxes due to ripple is approximately 50 % and occurs at energies above 30 keV. In positive shear plasmas without ICRH ripple reduction of D0 fluxes vanishes at energies below 10 keV. However, in the case of plasmas with low or reversed shear core, increased D0 fluxes were observed for energies below 10-20 keV in the presence of additional ripple and ICRH heating. Interpretive modeling of the deuterium neutral emission that accounts for the superbanana ripple diffusion of NBI ions is in reasonable agreement with measurements at least for the scenarios without ICRH. Note that ripples may essentially effect the fast ion confinement in ITER where TF ripple magnitude at the outer separatrix is expected to be δ ∼ 0.5%.

Ämnesord

NATURVETENSKAP  -- Fysik (hsv//swe)

NATURAL SCIENCES  -- Physical Sciences (hsv//eng)

Nyckelord

Energy ranges

Fast-ion confinement

Reversed shear

Ripple diffusion

Ripple effects

Ripple reduction

Separatrix

Shear plasmas

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