Tritium Pathways in JET Trace Tritium Transport Experiments
Recent JET experiments with transient puffed injection of low tritium levels (< 1%) have permitted detailed analysis of the time- and space-dependent neutron emission to determine the r*, n* and b scaling of particle transport in the core (normalized radius r<0.8) for ITB, ELMy H-mode and hybrid scenarios . Such 'trace T' experiments could also characterize the influence of the SOL on particle transport in the edge/pedestal region (0.8<r<1), although not designed for this purpose, since the ELM averaged radial influx of T+ ions at the edge of the core region (r=0.8) is provided by the neutron analysis and the external T2 gas puff rate is also measured. To see what can be learned about systematic SOL effects on particle transport scaling, using the available partial data, we analyze three representative gas puffing cases using NBI heating only, from the JET trace T experimental database, with parameters as given in the Table. The cases considered cover a range in average core electron density, but don't represent a density scan since plasma current, magnetic field and shape also vary. Further, there are systematic differences in ELM behavior for these cases, as shown in Fig.1.