(EX/P6-5) Analysis of Pedestal Characteristics in JT-60U H-mode Plasmas Based on Monte-Carlo Neutral Transport Simulation

Y. Nakashima1), Y. Higashizono1), H. Kawano1), H. Takenaga2), N. Asakura2), N. Oyama2), Y. Kamada2)
1) Plasma Research Centre, University of Tsukuba, Tsukuba, Japan
2) Japan Atomic Energy Agency, Naka Fusion Institute, 801-1 Mukouyama, Naka 311-0193, Japan

Abstract.  This paper describes the result 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 implemented and the simulation space is extended from SOL to core region. The present mesh model for DEGAS simulation has been developed based on the previous one for the DEGAS2 code and a consistency with the mesh model of the 2-D fluid UEDGE code has been ensured. In this simulation, therefore, background plasma parameters and the intensity of particle flux on the divertor plates are determined from the UEDGE code. The dependence of plasma density on the neutral penetration and ionization area was investigated in two cases of H-mode discharge with gas puff and without gas puff. The simulation result showed that the increase of edge pedestal density causes a noticeable decrease of 1/e scale length in the neutral penetration. Consequently the neutral penetration decreases with the increase of the density-pedestal width, which leads to the localization of ionization area near edge transport barrier (ETB) region. The detail of 3-D structure of neutral transport is also being investigated from the viewpoint of the local effect of the gas puff.

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