Comparison of Ne and Ar seeded radiative divertor plasmas in JT-60U

Nakano, Tomohide; JT-60 Team

Journal of Nuclear Materials, 463, p.555 - 560, 2015/08

https://doi.org/10.1016/j.jnucmat.2014.11.127

In H-mode plasmas with Ne, Ar and a mixture of Ne and Ar injection, the divertor radiation power fraction amongst these impurities in addition to an intrinsic impurity, C, is investigated. In plasmas with the inner divertor plasma attached, carbon is the biggest radiator, whichever impurites, Ne, Ar or a mixture of Ar and Ne is injected. In contrast, in plasmas with the inner divertor plasma detached, Ne is the biggest radiator due to a significantly high recombination radiation from Ne VIII. Ar is always a minor contributor in plasmas with the innder divertor both attached and detached.

Simulation study of power load with impurity seeding in advanced divertor "short super-X divertor" for a tokamak reactor

Asakura, Nobuyuki; Hoshino, Kazuo; Shimizu, Katsuhiro; Shinya, Kichiro*; Uto, Hiroyasu; Tokunaga, Shinsuke; Tobita, Kenji; Ono, Noriyasu*

Journal of Nuclear Materials, 463, p.1238 - 1242, 2015/08

https://doi.org/10.1016/j.jnucmat.2015.01.068

Arrangements of interlink divertor coils and divertor geometries for short super-X was proposed as the Demo advanced divertor design. Performance of plasma detachment under the large heat flux was investigated to optimize the divertor design, using SONIC simulation with Ar impurity seeding, where Pout = 500 MW, ne = 710 m at the core-edge boundary and the same diffusion coefficients for ITER simulation. Effects on the plasma temperature and density distributions were compared to the conventional divertor. The first run results with the same radiation power fraction of 0.92 in the conventional divertor showed that full detached plasma is produced, the maximum radiation region was maintained upstream the divertor target, and both the plasma heat load plus radiation load at the target was reduced to 10 MWmm level. Simulation for the lower radiation power fractions of 0.8-0.9 was also performed, and physics issues of the short super-X divertor are discussed.

SOL-divertor plasma simulations introducing anisotropic temperature with virtual divertor model

Togo, Satoshi*; Takizuka, Tomonori*; Nakamura, Makoto; Hoshino, Kazuo; Ogawa, Yuichi*

Journal of Nuclear Materials, 463, p.502 - 505, 2015/08

https://doi.org/10.1016/j.jnucmat.2014.09.081

A 1D SOL-divertor plasma simulation code introducing the anisotropic ion temperature with virtual divertor model has been developed. By introducing the anisotropic ion temperature directly, the second-derivative parallel ion viscosity term in the momentum transport equation can be excluded and the boundary condition at the divertor plate becomes unnecessary. In order to express the effects of the divertor plate and accompanying sheath implicitly, the virtual divertor model has been introduced which has an artificial sinks of particle, momentum and energy. The virtual divertor model makes the periodic boundary condition available. By using this model, SOL-divertor plasmas satisfying the Bohm condition has been successfully obtained. Also investigated are the dependence of the ion temperature anisotropy on the normalized mean free path of ion and the validity of the approximated parallel ion viscosity for the Braginskii expression and the limited one.

The Influence of gap geometry on impurity deposition and fuel accumulation in the castellated tungsten plasma-facing components exposed in EAST

Ding, F.*; Ashikawa, Naoko*; Fukumoto, Masakatsu; Katayama, Kazunari*; Mao, H.*; Ding, R.*; Xu, Q.*; Wu, J.*; Xie, C. Y.*; Luo, G.-N.*

no journal, ,