Conceptual Design of a Fast Wave Current Drive (FWCD) Coupler for the PLT

This paper describes the conceptual design of a Fast Wave Current Drive (FWCD) alumina ceramic loaded coupler for the Princeton Large Torus (PLT). An antenna capable of launching RF at 800 MHz was required. While phased waveguide arrays allow the coupling of correctly phased waves to the plasma, their large size (when used in air or vacuum) would preclude their application for PLT. However, the utilization of a dielectric loaded waveguide results in a reduction in size of waveguide elements by the square root of the dielectric constant^1,3. A description of the various approaches considered during the RF design, mechanical design, and component fabrication studies is included.