Alpha-particle physics in tokamaks

Efficient plasma heating by energetic fusion a-particles is a key element o f achieving ignition or high fusion gain regimes (Q >> 1) in a tokamak reac tor. The paper summarizes issues and reviews the latest theoretical and exp erimental results in the area of energetic particle physics in tokamaks. The discussion includes the classical physics of alpha-particle heating, ef fects of perturbations on a single-particle confinement, collective instabi lities driven by energetic alpha-particles, description of the potential al pha-particle loss channels and their impact on a design of the plasma-facin g components in a tokamak reactor. Most of the extrapolations to tokamak reactors are done with the use of ITE R parameters and operational scenarios as an example.