Monte Carlo Simulation of Particle Transport in the LID configuration

R. Kanno1,2), S. Jimbo2), H. Takamaru3) and M. Okamoto1,2)

1) National Institute for Fusion Science, Toki, 509-5292, Japan
2) Graduate University for Advanced Studies, Department of Fusion Science, Toki, 509-5292, Japan
3) Chubu University, College of Engineering, Department of Computer Science, Kasugai, 487-8501, Japan

Numerical simulation with Monte Carlo techniques is curried out in order to understand transport of charged particles in the peripheral region of the Large Helical Device (LHD) configuration with the Local Island Divertor (LID) [1,2]. The LID is one of the divertor concepts, and it utilizes an m/n=1/1 island formed at the edge region of the LHD. The island is generated by using the island control coils. The LID has been proposed to control the edge plasma of the LHD. Control of the edge plasma by means of the LID is expected to realize the high temperature divertor operation which leads to a significant energy confinement improvement. In the LID concept, the core region is surrounded by the island separatrix, and the field lines guide the outward heat and particle flux across the island separatrix to the LID head inserted into the island. In order to observe numerically the strike point pattern on the LID head, at first we consider transport of the mono-energetic particles created at a magnetic flux surface near the island separatrix. Previously, the strike point pattern was calculated by the field line tracing with the random walk process modeling the anomalous transport [3]. In the present study, the numerical observation of the pattern is improved; an orbit of a charged particle is given by solving the drift equation of the particle under effects of the collisions, i.e. the pitch-angle scattering and the energy scattering, etc. The particle motion within the m/n=1/1 island provides finally the strike point pattern on the LID head. We discuss the effects of the collisions on the strike point pattern and estimate changes of the pattern due to the anomalous transport modeled as the random walk process of the particle in the configuration space. We also make a comparison between the present study and the previous one [3].

References

[1] A. Komori, N. Ohyabu, et al., Plasma Physics and Controlled Fusion Research, (Vienna,1995).
[2] N. Ohyabu, A. Komori, et al., J. Nucl. Mater. 220-222 (1995) 298.
[3] T. Morisaki, S. Masuzaki, et al., J. Plasma Fusion Res. SERIES 3 (2000) 188.