No abstract

A self-consistent simulation, including a model for improved core energy confinement, demonstrates that externally applied, inductive current perturbations can be used to control both the location and strength of internal transport barriers (ITBs) in a fully non-inductive tokamak discharge. We find that ITB structures formed with broad non-inductive current sources such as LHCD are more readily controlled than those formed by localized sources such as ECCD. Through this external control of the magnetic shear profile, we can maintain the ITB strength which is otherwise prone to deteriorate when the bootstrap current increases. The inductive current perturbation, which can be implemented by a weak Ohmic power, offers steady-state, advanced tokamak reactors an external means of efficient ITB control for regulating the fusion-burn net output and spatial profile.