Transport measurements for confined non-thermal alpha particles in TFTR DT plasmas

Fusion produced non-thermal alpha particle radial profile measurements are obtained with the α-CHERS diagnostic in deuterium-tritium (DT) supershot plasmas on the Tokamak Fusion Test Reactor (TFTR). Alpha particles in the energy range 0.15 ≤ Eα ≤ 0.6 MeV are observed spectroscopically over a five point radial profile. The extracted non-thermal alpha signal is ≤ 1% of the background bremsstrahlung intensity for typical total fast alpha densities in the range (0.5-1.0) × 1017 m-3. The profiles obtained in two sets of discharges vary slightly, and are best described by a slowing down alpha distribution subject to neoclassical diffusion plus a small anomalous cross-field diffusion. The data are consistent with an effective anomalous diffusion coefficient in the range 0.00 ≤ Dα,a ≤ 0.10 m2/s, where Dα ,a is constant with alpha energy and with radius