Quasi-optical grill launching of lower-hybrid waves for a linearly increasing plasma density

An analysis of quasi-optical grills for lower-hybrid waves for heating and current drive purposes is presented. The tokamak plasma density versus the abscissa entering the plasma is assumed to behave like a step and a subsequent ramp. The study is performed by means of a two-dimensional formulation employing cylindrical waves. A detailed numerical analysis is presented, which allows us to show results for different configurations useful in practical cases and comparisons with the constant-density case.