FIRST MEASUREMENTS OF TRITIUM RECYCLING IN TFTR

The first spectroscopic measurements of tritium Balmer alpha (T-alpha) emission from a fusion plasma were made on TFTR using a Fabry-Perot interferometer. The tritium alpha (T-alpha) emission line is partially blended with the deuterium alpha (D-alpha) line, commonly used in edge plasma diagnostics, and the contributions of H-alpha, D-alpha and T-alpha 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 T-alpha line first became detectable in a high power, tritium only, neutral beam injection discharge at the level of T-alpha/(H-alpha + D-alpha + T-alpha) = 2%. Subsequently this ratio has increased to as high as 7.5%. Data on the time evolution of the T-alpha emission during a single discharge and over a series of tritium and deuterium discharges are presented.