First measurements of tritium recycling in TFTR

The first spectroscopic measurements of tritium Balmer alpha (T-α) emission from a fusion plasma were made on TFTR using a Fabry-Perot interferometer. The tritium alpha (Tα) emission line is partially blended with the deuterium alpha (Dα) line, commonly used in edge plasma diagnostics, and the contributions of Hα, Dα and Tα are separated by spectral analysis. The data are a measure of the fuelling of the plasma by tritium accumulated in the TFTR limiter, as well as the amount of neutral tritium generated by charge exchange of plasma ions. The Tα line first became detectable in a high power, tritium only, neutral beam injection discharge at the level of Tα (Hα + Dα + Tα) = 2%. Subsequently this ratio has increased to as high as 7.5%. Data on the time evolution of the Tα emission during a single discharge and over a series of tritium and deuterium discharges are presented. (author). 33 refs, 7 figs