The positive-ion based NBI system for JT-60 began operation in 1986 with hy
drogen beam, and had injected the neutral beam power of 27 MW at 75 keV. Th
e beam species has been changed to deuterium through changing the ion sourc
es and beam-line components in 1991. The NBI has injected a deuterium beam
of 40 MW at 96 keV in 1996. In 2000, the computer control system for the be
am operation has been changed from a mini-computer to a workstation system
in order to match a great variety of beam injection parameters, and the ope
ration capability has greatly improved.