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In lower hybrid current drive (LHCD) experiments in the Joint European Torus (JET), up to 7.3 MW LH power has been coupled to X-point plasmas, resulting in sawtooth suppression and full current drive up to 3MA. The current drive efficiency reached eta (CD) = 0.26 E20 m{-2} A/W in these experiments. The LH power deposition and driven current profiles can quite well be reproduced with the ray-tracing + Fokker-Planck code in JET, even when multi-pass absorption of the LH wave is dominant. Profile control with off-axis LHCD has been used for increasing q above 1, thereby suppressing sawteeth before and during the edge-localized mode (ELM)-free hot ion H-mode. In optimized shear plasmas, a broad q-profile with central negative shear was formed with moderate LH power (</= 2 MW), applied in the low density phase during the current ramp-up. An internal transport barrier with improved electron confinement was produced, which resulted in a peaking of the electron temperature profile and T(e0) up to 10 keV at n(e) approximately equal to 1E19 m{-3}. LHCD has assisted in producing the target q-profile required for high fusion yield in the optimized shear experiments.

Additional information

Authors: EKEDAHL A ET AL, JET Joint Undertaking, Abingdon, Oxon (GB)
Bibliographic Reference: Report: JET-P(97)47 EN (1997) 15pp.
Availability: Available from the Publications Officer, JET Joint Undertaking, Abingdon, Oxon, OX14 3EA (GB)
Record Number: 199810249 / Last updated on: 1998-03-09
Original language: en
Available languages: en