Combline antennas for launching traveling fast waves

The combline structure shows promise for launching traveling fast magnetosonic waves with adjustable n∥ (3≤n∥≤6) for current drive. In this paper, the dispersion and damping properties of the combine antenna with and without a Faraday shield are given. The addition of a Faraday shield which eliminates the electrostatic coupling between current straps as well as between the straps and plasma offers the advantage of eliminating the need for the lumped capacitors which are otherwise required with this structure. The results of vacuum dispersion and damping measurements on a low power model antenna are also given.