P. de Vries

Tritium transport experiments on the JET tokamak

An overview is given of the experimental method, the analysis technique and the results for trace tritium experiments conducted on the JET tokamak in 2003. Observations associated with events such as sawtooth collapses, neo-classical tearing modes and edge localized modes are described. Tritium transport is seen to approach neo-classical levels in the plasma core at high density and low q(95), and in the transport barrier region of internal transport barrier (ITB) discharges. Tritium transport remains well above neo-classical levels in all other cases. The correlation of the measured tritium diffusion coefficient and convection velocity for normalized minor radii r/a = [0.65, 0.80] with the controllable parameters q95 and plasma density are found to be consistent for all operational regimes (ELMy H-mode discharges with or without ion cyclotron frequency resonance heating, hybrid scenario and ITB discharges). Scaling with local physics parameters is best described by gyro-Bohm scaling with an additional inverse beta dependence.

Statistical comparison of ICRF and NBI heating performance in JET-ILW L-mode plasmas

After the change over from the C-wall to the ITER-like Be/W wall (ILW) in JET, the radiation losses during ICRF heating have increased and are now substantially larger than those observed with NBI at the same power levels, in spite of the similar global plasma energies reached with the two heating systems. A comparison of the NBI and ICRF performances in the JET-ILW experiments, based on a statistical analysis of ∼3000 L-mode discharges, will be presented.

EFD-C(13)03/32 ITER Like Wall Impact on MHD Instabilities in JET Discharges

1Consorzio RFX, EURATOM-ENEA Association, Corso Stati Uniti 4, 35127 Padova, Italy 2Euratom/CCFE Fusion Association, Culham Science Centre, Abingdon, OX14 3DB, UK 3Associazione EURATOM-ENEA sulla Fusione, C.R. Frascati, Roma, Italy 4Association EURATOM-CEA, CEA/DSM/IRFM, Cadarache 13108 Saint Paul Lez Durance, France 5Associacao EURATOM/IST, Instituto de Plasmas e Fusao Nuclear, Instituto Superior Tecnico, Av Rovisco Pais, 1049-001 Lisbon, Portugal 6FOM institute DIFFER, EURATOM association, P.O. Box 1207, Nieuwegein, Netherlands 7Max-Planck-Institut fur Plasmaphysik, EURATOM-Assoziation, D-85748 Garching, Germany 8Associazione EURATOM-ENEA sulla Fusione, Universita di Roma, Italy

ICRF heating scenarios in JET with emphasis on 4He plasmas for the non-activated phase of ITER

In the initial phase of ITER operation, 4He plasmas could be used in order to avoid activating the machine. The main ICRH scenarios foreseen for ITER 4He plasmas are (3He)4He and (H)4He. ICRH experiments have been carried out on JET using 4He plasmas to validate these scenarios. At the same time, conditions for access to H-mode in plasmas of various isotope compositions from dominantly 4He to dominantly D have been studied. Experiments have also been carried out for the first time in 4He plasmas with the ICRF power added to 4He neutral beam injection at the third harmonic of 4He in order to produce a 4He tail for alpha particle studies.