EFFECTS OF EDGE AND CENTRAL FUELING ON PARTICLE CONFINEMENT IN JT-60U

In order to understand the effects of the particle source distribution on the global particle confinement, the particle balance in JT-60U ha s been quantitatively analyzed. The dependence of the particle confine ment time on the ratio of the central fuelling due to NBI to the edge fuelling due to wall recycling and gas-puffing was investigated. It wa s found that the particle confinement time increased with this ratio f or the L-mode and ELMy H-mode plasmas, while, for the ELM-free H-mode plasma, the dependence of the particle confinement time on this ratio was not obvious. Furthermore, the confinement times of the center and edge fuelled particles were separated for the L-mode plasma. It was al so found that the confinement time of the center fuelled particles was about 3 times longer than that of the edge fuelled particles.