Ion sources in neutral beam injection system and its applications

A neutral beam injection (NBI) system and an ion source used in the NBI system are briefly described with a view to applying them to the material science fields. A positive ion source in the present NBI system provides the current density of 250 mA/cm2 and the beam divergence angle of less than 1deg at the energy of 80 keV/nucleon. Development of a negative ion source required in the future NBI system with the injection energy of more than 500 keV is also described. The ion source in the NBI system has a possibility to be applied to the various fields for its superior characteristics such as uniformity in wide area, high current and power density, and low beam divergence. (author)