The main topics concerning lower hybrid wave heating (LHH) and lower hybrid current drive (LHCD) in tokamak systems are presented. The inherent properties of tokamak the other hand, induce a consumption of wave energy by the trapped electrons, which reduce the current drive efficiency. The methods for the enhancement of the current drive efficiency may be derived from detailed analyses by drawing upon the ray tracing technology on toroidal geometry and the Fokker-Planck theory on velocity space.
