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Feng,  Y.

Kawamura,  G.

Kobayashi,  M.

Masuzaki,  S.

Morisaki,  T.

Tomita,  Y.

NIFS-Repository (National Institute for Fusion Science)

Simulation of impurity transport in a fusion de-vice is an important issue related to energy conﬁne-ment and life time of plasma-facing components. Wehave developed one-dimensional ﬂuid model of LHD di-vertor plasma and applied it to ERO1, 2). The three-dimensional distribution of plasma is, however, impor-tant for quantitative analysis of impurity transport. Al-though the plasma transport code, EMC3-EIRENE3),is used to simulate the ergodic layer, i.e. edge/SOL,in LHD, the calculation grid does not include divertorplasma. Technical study of generation method of thegrid covering the ergodic and divertor plasma was car-ried out.The magnetic shear is strong near the vacuum ves-sel and causes strong distortion on the grid. That makesit diﬃcult to generate a grid covering whole volume inthe vacuum vessel because the grid of EMC3, i.e. plasmaﬂuid code, have to be aligned to the magnetic ﬁeld lines.EIRENE code, i.e. neutral particle code, does not re-quire the ﬁeld-aligned grid in three dimension, thereforewe split the volume to three class of regions, i.e. ergodicregion, divertor leg region and vacuum region. We devel-oped a series of tools to generate grids for each region.Guidelines of boundaries are manually made and a mag-netic ﬁeld tracing code, KMAG4), is utilized for ergodicand leg regions. Geometrical method was developed tomake vacuum grids.The generated grids are shown in Fig. 1. The ﬁguresare on a poloidal cross section in a horizontally elongatedplane. They share the same points in boundaries and areconnected each other in EMC3-EIRENE. The simulationbox has the size of 18◦ in the toroidal direction. Theperiodicity and up-down symmetry in horizontally andvertically elongated planes are utilized to reduce the sizeof the box. We made grids on planes par 1◦.A simulation to test the consistency of grids wascarried out. The distribution of electron temperature isshown in Fig. 2. The proﬁle is continuous through theboundaries of grids. We obtained other distributions ofconnection length, electron density and Mach number.These quantities were physically reasonable. Thereforewe conclude that the new calculation grid is technicallyvalid. The vacuum grids are, however, not complete forneutrals because of distortion coming from the boundaryshape. In order to ﬁx the problem, reconstruction withoptimization are necessary. The optimized grid and de-velopment of automated generation tools are future is-sues.1) A. Kirschner et al., Nucl. Fusion 40 (2000) 989.2) G. Kawamura et al., Plasma Fus. Res., 5 (2010)S1020.3) M. Kobayashi et al.,fusion science technology, 58(2010) 220.4) Y.Nakamura, J. Plasma Fus. Res., 69 (1993) 41(a)(b)(c)Fig. 1: Generated grids for each region; (a) ergodicregion, (b) leg region, (c) vacuum region.Fig. 2: Contour plot of electron temperature.197§7. Extension of Calculation Grid for LHD Edge and Divertor PlasmasKawamura, G., Kobayashi, M., Masuzaki, S., Morisaki, T., Tomita, Y.,  Feng, Y. (Max-Plank-Institut für Plasmaphysik, Graifswald Germany)

Extension of Calculation Grid for LHD Edge and Divertor Plasmas

Extension of Calculation Grid for LHD Edge and Divertor Plasmas

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