Modeling of L-H/H-L transition in TSC simulation using JT-60U experimental data

Miyamoto, Seiji; Nakamura, Yukiharu*; Hayashi, Nobuhiko; Oyama, Naoyuki; Takenaga, Hidenobu; Sugie, Tatsuo; Kusama, Yoshinori; Yoshino, Ryuji

The neutral dynamics including fueling, divertor pumping, charge exchange penetration, wall retention and so on would complicate the analysis of ITER plasma behavior such as H-L back transition during plasma current ramp-down. Recently, a relatively simple model of neutral dynamics was developed by us with TSC code to describe the plasma behavior during L-H and H-L transition phase. This model is compared with a JT-60U shot, in which it is possible to extract the effect of particle confinement change on neutral because H-mode discharge is switched on/off according to EC injection and thereby particle source density is kept constant during transition. It is shown that TSC simulation can account the behavior of neutral inferred from the experimental D signal. It is concluded that this model is applicable to scenario development of the ITER.