ECRH current drive in tokamak plasmas

The current drive by electron cyclotron resonance heating (ECRH) is investigated in a typical magnetic field of tokamak with circular cross section. The trapped electrons and the modification of electron-cyclotron resonance condition by the relativistic mass increase are shown to have significant effects on the efficiency of this current drive. The efficiency strongly depends on the values of the parallel velocity u0 of resonant electrons, the inverse aspect ratio ε, the poloidal angle θ0 of absorption point, and the relativistic parameter S, which represents the strength of the relativistic correction to the resonance condition. (author)