JET quasistationary internal-transport-barrier operation with active control of the pressure profile

Quasistationary operation was achieved in discharges where a well developed internal-transport barrier (ITB) was present both on ion and electron species, showing, for the first time, that some key features of the concept of advanced tokamak can be viable in a steady state reactor perspective. This was possible by using the lower hybrid current drive (LHCD) power in order to achieve a full current drive scenario and to "freeze" the current density profile. The implementation, for the first time, of an active feedback on the electron temperature gradient allowed a successful direct control of the requested preprogrammed quantities.