Wave launcher heating studies in the ion cyclotron frequency range. Progress report

This progress report discusses our work on the analysis, design, fabrication and laboratory measurements on ion cyclotron frequency range (ICRF) waveguide launchers. We have developed a computer code to solve for the surface impedance for a fast ICRF wave emanating from a dielectric filled guide in the presence of a divertor H-mode or L-mode plasma edge density profile. The H-mode with a density pedestal causes an increased, although tolerable wave reflection from the plasma. We have also formulated a computer code to analyze both vacuum ridged and folded-guide launchers. We have published work on scattering matrix formalism and developed a computer code to determine the coax probe size and distance to a sliding short to match the incident coax wave to the outgoing plasma ICRF wave emanating from the guide for general plasma impedances. We have made detailed measurements on a fabricated waveguide launcher for the cases of both air and de-ionized, distilled water-filled guides. The coax to waveguide transition for the matched water-filled dielectric guide case has a minimum power reflection coefficient of 6.3% at 90.8 MHz. We have also begun to consider coupling from ion Bernstein wave, folded and ridged vacuum-filled waveguide launchers