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Numakura, Masahiko*; Sato, Nobuaki*; Bessada, C.*; Okamoto, Yoshihiro; Akatsuka, Hiroshi*; Nezu, Atsushi*; Shimohara, Yasuaki*; Tajima, Keisuke*; Kawano, Hirokazu*; Nakahagi, Takeshi*; et al.
Progress in Nuclear Energy, 53(7), p.994 - 998, 2011/11
Times Cited Count：13 Percentile：67.73(Nuclear Science & Technology)X-ray absorption fine structure (XAFS) measurements on thorium fluoride in molten lithium-calcium fluoride mixtures and molecular dynamics (MD) simulation of zirconium and yttrium fluoride in molten lithium-calcium fluoride mixtures have been carried out. In the molten state, coordination number of thorium and inter ionic distances between thorium and fluorine in the first neighbor are nearly constant in all mixtures. However the fluctuation factors (Debye-Waller factor and C
cumulant) increase until 
CaF
= 0.17 and decrease by addition of excess CaF. It means that the local structure around Th
is disordered until CaF=0.17 and stabilized over CaF = 0.17. The variation of fluctuation factors is related to the number density of F
in ThF
mixtures and the stability of local structure around Th increases with decreasing the number density of F in ThF mixtures. This tendency is common to those in the ZrF and YF mixtures.
Nakashima, Yosuke*; Higashizono, Yuta*; Kawano, Hirokazu*; Takenaga, Hidenobu; Asakura, Nobuyuki; Oyama, Naoyuki; Kamada, Yutaka
Proceedings of 22nd IAEA Fusion Energy Conference (FEC 2008) (CD-ROM), 8 Pages, 2008/10
This paper describes the results of pedestal characteristics in H-mode plasmas of JT-60U based on neutral transport simulation using the DEGAS Monte-Carlo code. A three-dimensional (3-D) mesh structure including isolated dome, baffle and divertor plates is precisely built-up and the simulation space is extended from SOL to core plasma region. In this simulation background plasma parameters and the intensity of particle flux on the divertor plates are determined from the UEDGE plasma code. The dependence of plasma density on the neutral penetration and ionization area were investigated in two cases of ELMy H-mode discharge with gas puffing and without gas puffing. The simulation results showed noticeable differences in 1/e scale length in the neutral penetration and in ionization width near edge transport barrier region. Dependence of the plasma density from the pedestal edge to SOL region on the ionization region and the 3-D effect of local gas puffing are discussed in terms of neutral transport.
Nakashima, Yosuke*; Higashizono, Yuta*; Kawano, Hirokazu*; Takenaga, Hidenobu; Asakura, Nobuyuki; Oyama, Naoyuki; Kamada, Yutaka; Yatsu, Kiyoshi*
Journal of Physics; Conference Series, 123, p.012029_1 - 012029_7, 2008/00
Times Cited Count：4 Percentile：77.44(Physics, Fluids & Plasmas)The first results of a fully three-dimensional (3-D) Monte-Carlo simulation using DEGAS ver.63 code applied to the JT-60U tokamak and analysis of neutral behavior in H-mode plasmas are described. A precise mesh structure including isolated dome, baffle and divertor plates is built-up and the simulation space is extended from SOL/divertor to core plasma region. Benchmarking with 2-dimensional simulation with the DEGAS2 code successfully showed the validity of the present simulation. Result of 3-D simulation in the JT-60U plasma with gas puffing indicates the significant localization of neutrals around the gas puffer and the detail of neutral diffusion in toroidal and poloidal directions are clarified. The dependence of plasma density on the neutral penetration and ionization area are also discussed in different H-mode discharges.
Owaki, Hirokazu; Sugihara, Masayoshi; Kawano, Yasunori; Lukash, V. V.*; Khayrutdinov, R. R.*; Zhogolev, V.*; Ozeki, Takahisa; Hatayama, Akiyoshi*
Europhysics Conference Abstracts (CD-ROM), 29C, 4 Pages, 2005/00
no abstracts in English
