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Scientific and technical activities on JET focus on the issues likely to affect the ITER design and operation. Our understanding of the ITER reference mode of operation, the ELMy H-mode, has progressed significantly. The extrapolation of ELM size to ITER has been re-evaluated. Neoclassical tearing modes have been shown to be meta-stable in JET, and their beta limits can be raised by destabilization (modification) of sawteeth by ion cyclotron radio frequency heating (ICRH).

Alpha simulation experiments with ICRH accelerated injected {4}He beam ions provide a new tool for fast particle and magnetohydrodynamic studies, with up to 80�90% of plasma heating by fast {4}He ions. With or without impurity seeding, a quasi-steady-state high confinement (H(98) = 1), high density (n(e)/n(GW) = 0.9�1) and high beta (beta(N) = 2) ELMy H-mode has been achieved by operating near the ITER triangularity (delta ~ 0.40�0.5) and safety factor (q(95) ~ 3), at Z(eff ) ~ 1.5�2. In advanced tokamak (AT) scenarios, internal transport barriers (ITBs) are now characterized in real time with a new criterion, roh*(T).

Tailoring of the current profile with lower hybrid current drive provides reliable access to a variety of q profiles, lowering access power for barrier formation. Rational q surfaces appear to be associated with ITB formation. Alfvén cascades were observed in reversed shear plasmas, providing identification of q profile evolution. Plasmas with 'current holes' were observed and modelled. Transient high confinement AT regimes with H(89) = 3.3, beta(N) = 2.4 and ITER-relevant q < 5 were achieved with reversed magnetic shear.

Quasi-stationary ITBs are developed with full non-inductive current drive, including ~ 50% bootstrap current. A record duration of ITBs was achieved, up to 11s, approaching the resistive time. For the first time, pressure and current profiles of AT regimes are controlled by a real-time feedback system, in separate experiments. Erosion and co-deposition

Additional information

Authors: PAMELA J, EFDA Close Support Unit, Culham Science Centre, Abingdon, Oxon (UK);SOLANO E R, EFDA Close Support Unit, Culham Science Centre, Abingdon, Oxon (UK)
Bibliographic Reference: An article published in: Nucl. Fusion 43 (2003) 1540�1554 PII: S0029-5515(03)68825-3
Availability: This article can be accessed online by subscribers, and can be ordered online by non-subscribers, at:
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