Abstract
In steady-state tokamak fusion reactors, an efficient external current drive and a large fraction of the bootstrap current are required for non-inductive operation at low circulating power. NBI is a powerful and reliable actuator for the current drive and heating. A negative-ion based NBI (N-NBI) with a high beam energy more than 350 keV has been installed in the JT-60U tokamak in order to study the NBI current drive and heating in an ITER relevant regime. This paper presents recent achievements in N-NBI experiments and progress of the JT-60U N-NBI system for steady-state operation in ITER and tokamak fusion reactors.
