Effects of source distribution and edge density on particle confinement in JT-60U

Abstract

In order to understand the effects of source distribution and edge density on global particle confinement, local particle transport has been analysed for the L mode plasma of JT-60U. The density in the main plasma is maintained not only by the particle source in the main plasma but also by the edge density. When the edge density is not zero, the density in the main plasma takes some value, even if there is no particle source in the main plasma. This density is called the `base density', which is not related to the particle source in the main plasma. In this paper, the base density and the densities maintained by neutral beam injection (NBI) and wall recycling sources were separated. It was found that although the penetration depth of NBI particles was 10 times greater than that of the wall recycling particles, the particle confinement time of the NBI particles was not so large compared with that of the wall recycling particles because of the edge density and strong inward pinch. It was also found that when the base density was taken into account, the particle confinement times of the NBI and wall recycling particles were reduced by more than 50%