Controlling the internal transport barrier oscillations in high-performance tokamak plasmas with a dominant fraction of bootstrap current

It is shown that relaxation oscillations associated with repetitive internal transport barrier (ITB) buildup and collapse in high-performance, overdriven tokamak plasmas, with ion-cyclotron resonance heating (ICRH), neutral-beam injection (NBI) and lower-hybrid current drive (LHCD), and with a dominant fraction of bootstrap current, can be overcome if the LHCD power is sufficiently high. This result has been obtained using a benchmarked, fully predictive transport model iterated with given ICRH profiles and self-consistently with NBI and LHCD modules, the stabilizing role of the E × B flow shear being combined with that of reversed magnetic shear in the simulation of ITB dynamics.