Beam divergence and power loading on the beamline components of the negative-ion based NBI system for JT-60U

In JT-60U, a high-energy neutral beam injection (NBI) program using negative-ion based NBI (N-NBI) for non-inductive current drive and core plasma heating studies in high-density plasma has progressed. The target performance of the N-NBI is a neutral beam injection power of 10 MW for 10 s at 500 keV. A neutral beam power of 5.2 MW at 350 keV with deuterium has already been injected into JT-60U plasma. The beam divergence and power loading onto the beamline components are two important items to evaluate beam performance. The beam divergence, estimated roughly from heat loads at the beam drift duct in beam injection experiments into JT-60U plasma, was around 4 mrad for the horizontal direction and 6 mrad for the vertical direction, which were close to the design values of 5 mrad. The power loading on beamline components were reasonable as compared with the design value. (C) 2001 Elsevier Science B.V. All rights reserved.