 |
 |
 |
H. Takenaga, K. Nagashima, A. Sakasai,
N. Asakura, K. Shimizu, H. Kubo, S. Higashijima,
T. Oikawa, T. Fujita, Y. Kamada, N. Hosogane,
M. Shimada and the JT-60 Team
Japan Atomic Energy Research Institute, Naka Fusion Research Establishment Naka-machi, Naka-gun, Ibaraki-ken, 311-0193, Japan
Abstract. Particle confinement and transport have been systematically analyzed
for the improved confinement modes in JT-60U. A scaling law for the total
number of ions in the main plasma of ELMy H-mode plasmas was proposed for the
first time with confinement times of the particles supplied by NBI (center
fuelling) and by recycling and gas-puffing (edge fuelling) separately
defined. The confinement time increases and decreases with density for center
and edge fuelling, respectively. The comparison between the experimental data
and the scaling was made for the high bp ELMy H-mode and reversed shear
plasmas. The particle confinement was enhanced over the scaling by a factor of
about 2 in the reversed shear plasma. The particle diffusivity and convection
velocity were also evaluated based on the perturbation technique using
modulated helium gas-puffing in ELMy H-mode and reversed shear plasmas. The
particle diffusivity and convection velocity were estimated to be
0.4 - 2m2/s and -5.5 (inward) 
+ 2.5 (outward) m/s for the ELMy H-mode plasma
and to be
0.2 - 2m2/s and -4 (inward) 0 m/s for the reversed
shear plasma, respectively. The particle diffusivity was reduced by a factor
of 5-6 around the internal transport barrier compared with that in the outside
and inside regions in the reversed shear plasma.
IAEA 2001
