Alpha heating predictions for DT supershots

Since alpha heating is essential for tokamak fusion power, a demonstration of alpha heating would be an important milestone. This paper discusses predictions of alpha heating and ways to measure alpha heating in TFTR during DT operation. Alpha heating is expected to increase the electron temperature near the center of long duration, high performance DT supershots during the late neutral beam injection (NBI) phase by ∼ 1 keV above that of similar DD supershots. Measurable increases in Te are expected also during reheating after the post-NBI sawteeth, and possibly during alpha heating in post-NBI pellet-fueled discharges. Competing effects, such as differences in the D and T neutral beam parameters will also change the central Te, so a careful choice of discharges and accurate modeling will be needed to identify alpha heating. We discuss predictions based on TFTR experiments designed to optimize supershots for use during the DT alpha heating experiment scheduled to start in the fall of 1993. (author) 5 refs., 4 figs