Multi-pellet injection in TFR

Four successive hydrogen pellets have been injected into deuterium plasma of the TFR Tokamak (major radius R = 0.98 m, minor radius a = 0.2 m). Each pellet corresponds to 50 % of the initial average density and penetrates at about half radius. After filling up, the density profile generally hollow just after injection, evolves slowly towards a slightly more peaked shape. Transport analysis of the long time scale density relaxation shows generally no change in particle transport coefficients, except in a particular case where the time interval between two pellets has been reduced from ∼ 40 ms to ∼ 20 ms