Improved Measurements of Injected Electron Cyclotron Power in DIII-D

Direct measurements of the rf power injected into the DIII-D tokamak from the ECH gyrotrons are being made using a high power dummy load at the tokamak. The measurements will permitt power monitors, which measure the rf leakage from well-aligned gaps in the vacuum waveguides near the tokamak, to be calibrated for various elliptical polarizations of the rf propagating in the HE$_{11}$ waveguide mode. Using these measurements, correlations with calorimetric measurements of the gyrotron cooling circuits, the usual basis for rf power measurements in the system, will be made. Low power rf measurements and theoretical and experimental estimates of the transmission efficiencies of the individual components in the transmission lines will be compared with the direct measurements.