Transport of Recycled Deuterium to the Plasma Core in TFTR

We report a study of the fueling of the plasma core by recycling in the Tokamak Fusion Test Reactor (TFTR) [Phys. Plasmas 2, 2176 (1995)]. We have analyzed discharges fueled by deuterium recycled from the limiter and tritium-only neutral beam injection. In these plasmas, the DT neutron rate provides a measure of the deuterium influx into the core plasma. We find a reduced influx with plasmas using lithium pellet conditioning and with plasmas of reduced major (and minor) radius. Modeling with the DEGAS neutrals code shows that the dependence on radius can be related to the penetration of neutrals through the scrape-off layer