Tritium recycling and retention in JET

Abstract JET's 1997 Deuterium TritiumExperiment (DTE1) allows a detailed study of hydrogenic isotope recycling and retention in a pumped divertorconfiguration relevant to ITER. There appear to be two distinct forms of retained tritium. (1) A dynamic inventory which controls the fueling behaviour of a single discharge, and in particular determines the isotopic composition. This is shown to be consistent with neutral particleimplantation over the whole vessel surface area. (2) A continually growing inventory, which plays a small role in the particle balance of a single discharge, but ultimately dominates the hydrogenic inventory for an experimental campaign comprising thousands of pulses. This will be the dominant retention mechanism in long-pulse devices like ITER. The JET retention scaled-up to ITERproportions suggests that ITERmay reach its tritiuminventory limit in less than 100 pulses.