Thermal performance of the launcher mirrors in the DIII-D ECH system

The DIII-D ECH system includes three launcher assemblies each of which can accommodate the RF beams from two gyrotrons. The launchers use four different designs for the mirrors which focus and direct the beams into the tokamak. The designs use molybdenum brazed to graphite, thin Glidcop or variable thickness Glidcop. A fourth design with laminated Glidcop/stainless steel construction has been operated, but no thermal data are available. All the mirrors operate without active cooling. This paper presents preliminary analyses and measurements of the thermal performance of the three designs for which data have been obtained.