Optimization of microwave reflection gratings for electron cyclotron resonance heating in O2 mode

For the application as in-vessel microwave mirrors in fusion reactors, for which the geometry cannot be freely chosen, microwave reflection gratings are being optimized with respect to single order diffraction efficiencies and polarisation independent phase behavior. By simulations using the boundary element method (BEM), which is very fast for this purpose, it is possible, to obtain numerical optimization of Fourier gratings, resulting in almost perfect (efficiency >99%) grating structures.