Carbon fiber composite (CFC) materials have been used as the plasma facing surface on limiters in TFTR since 1989. We changed from all POCO graphite tiles on the inner bumper limiter (BL) to about 1/3 CFC tiles in the high heat flux area because of tile failures with heating powers up to 20 MW. The RF limiters (RFL), which were designed to protect the radio-frequency antennas from plasma heat flux, were designed with CFC material. This paper discusses the design issues related to the CFC materials, our experience with material property variations in large production runs, and our operational experience with CFC limiters. The replacement BL tiles were made from a 3D CFC material. The RFL tiles were made from a 2D CFC. The use of 2D CFC material was molded to near net shape. The tiles were required to withstand up to 105 cycles of 50 MW of heating power for a duration of 2 s. Determination of the minimum material properties was one of the major design issues. The fabrication of the BL tiles required production of about 35 large billets of 3D CFC material. The fabrication of the RFL tiles required production of about 160 tile blanks. We found substantial variation in the material properties of the finished parts. The distribution of the material property data is discussed. In the case of the RFL tiles some parts did not meet the required properties because of the non-standard nature of the fabrication. After nearly two years of operation on the CFC tiles, none of the CFC tiles have failed. The only damage observed on the CFC tiles is a slight darkening of the tile when it is heated to the sublimation point by the disruption heat loads. Recommendations of the best design and fabrication strategies for CFC plasma facing components are made.
