Quasi-Optical Propagation of an EC Gaussian Beam, Absorption and Current Drive in Tokamaks

The issue of quasi-optical propagation of a Gaussian beam of electron cyclotron waves, and of the power absorption and driven current is reviewed for the case of a general tokamak equilibrium. The propagation of a general astigmatic Gaussian beam is described in terms of a set of quasi-optical rays which describe diffraction effects, within the framework of the complex eikonal approach. The absorbed power and the driven current density are computed along each ray solving the fully relativistic dispersion relation for electron cyclotron wave and by means of the neoclassical response function for the current. Results obtained with the new code GRAY in ITER are presented