Hybrid and Steady-State Operation on JET and Tore Supra

Producing fusion energy requires to simultaneously sustain in a tokamak environment fully non inductive regimes at the highest Q-values and a 'significant' fusion performance level under MHD-stable conditions, while insuring a satisfactory confinement of the fast alpha particles. This ambitious goal is being investigated on many devices worldwide, particularly focusing on the role played by the current density profile. The paper reports on the recent experimental progress of both the JET and Tore Supra devices towards i) long to very long pulse operation relying on a careful use of lower hybrid current drive under various current profile tailoring conditions (namely so-called 'hybrid' peaked current density profiles and so-called 'steady-state' hollow current density profiles) and ii) discharges performed with real-time controlled pressure and/or current density profiles. Such discharges are detailed and interpreted using the CRONOS integrated modelling suite. Its fully predictive capability, including real time control features, is used to provide keys to future experiments