Trace tritium transport in JET

Trace amounts of tritium (1-5% of the deuterium content) were introduced in short puffs ( ~ 40 ms) into the low field midplane edge of steady state deuterium plasmas in JET. The transport properties of the edge and core plasma, and the time evolution of the fraction of tritium in the recycling flux, determine the evolution in space and time of the 14 MeV neutron emission following these puffs. The derived tritium transport coefficients were used to model the deuterium density profile. Good agreement of the profile shape was found near the edge. In the core, the predicted deuterium density is more peaked than the measured profile. An attempt was made to study the scaling of tritium transport with dimensionless plasma parameters. For H mode discharges the transport is best described by gyro-Bohm scaling in the core and Bohm scaling near the edge. These conclusions are based on the assumption that the dependence of particle transport on b and n* is weak within the range of variation in these parameters in the data set.