Particle Beam Application. Present Status and Future Prospective. Neutral Particle Beams for Plasma Heating in Magnetic Confinement System. Development of Neutral-Beam-Injection System and Plasma Heating Characteristics.

A neutral beam injection (NBI) system employed in magnetic fusion devices is overviewed with respect to both its technological aspects and plasma heating characteristics. Since a negative-ion-based NBI system is essential for plasma heating in the fusion reactor, technical problems to be solved and physical subjects to be clarified are discussed related to the negative-NBI. The acceleration of intense negative ion beams of over 1 MeV and continuous operation of the negative ion source for over 1 year are necessary, as for the technical issues. As for the physical issues, achievment of a high ion temperature is required in high energy NBI heating with which the plasma electrons are mainly heated, as well as that of an efficient current drive in high-density plasmas.