Plasma heating & RF, an introduction

The additional heating and non-inductive current-drive methods are reviewed. First, the limitations of ohmic heating in tokamaks are examined and the motivations for using additional heating in tokamaks or other machines are discussed. Next we sketch the principles of heating by injection of fast neutrals - or Neutral Beam Injection (NBI). The principle of the injector is briefly outlined, but we focus on the processes by which the beam transfers energy to the plasma: the ionization and slowing-down processes. Next, we make a review of the different heating schemes based on the injection of electromagnetic energy into the plasma. We list the different wave heating frequency ranges and sketch the propagation and damping peculiarities in each domain. Heating in the Alfven and lower hybrid wave domains are described in some more details.