A spectroscopic diagnostic for measurement of slowing‐down alpha particles is under development and will be implemented for D–T operation of the Tokamak Fusion Test Reactor. The visible 468.6 nm He+line (n=3–4) is excited by charge exchange recombination of alphas with a heating neutral beam (55 keV/amu), and the distortion of the line profile caused by alphas with energies up to 0.5–1.0 MeV is observed. Expected intensities are 0.1%–10% of the bremsstrahlung background for D–T discharges withQ=0.2–1.0. Because the signal is small, a high‐throughput optical system is needed to achieve the desired signal‐to‐noise ratio of 10–100. Vertical and horizontal arrays of sightlines with five spatial channels will be used. Initially, two spatial channels will be coupled via fiber optics to anf/3.8 spectrometer equipped with a low‐noise charge coupled device detector, with expansion to 5–10 spatial channels planned for D–T operation.