Numerical studies on the use of a quasi-optical grill to couple lower hybrid waves to a plasma, for current drive in tokamaks, are currently under way. Study of the coupling has been carried out in a rigorous way, through the solution of scattering from cylinders with parallel axes in the presence of a plane of discontinuity for electromagnetic constants. Here we restrict our attention to the case of a plasma with a step density profile and report some results on launched spectra, coupled power and directivity.
Frezza F, Gori F, Santarsiero M, Santini F, & Schettini G (1995). Full-wave theory of a quasi-optical launching system for lower-hybrid waves: the step density case. FUSION ENGINEERING AND DESIGN, 26, 361-464.