Chapter 5: Physics of energetic ions

Physics knowledge (theory and experiment) in energetic particles relevant t o design of a reactor scale tokamak is reviewed, and projections for ITER a re provided in this Chapter of the ITER Physics Basis. The review includes single particle effects such as classical alpha particle heating and toroid al field ripple loss, as well as collective instabilities that might be gen erated in ITER plasmas by energetic alpha particles. The overall conclusion is that fusion alpha particles are expected to provide an efficient plasma heating for ignition and sustained burn in the next step device. The major concern is localized heat loads on the plasma facing components produced b y alpha particle loss, which might affect their lifetime in a tokamak react or.