# Plasma and Fusion Research

## Volume 14, 1203091 (2019)

# Rapid Communications

- Graduate School of Engineering, Osaka University, Suita 565-0871, Japan
- 1)
- National Institutes for Quantum and Radiological Science and Technology, Rokkasho 039-3212, Japan

### Abstract

An ingenious model for large-scale electromagnetic (EM) plasma simulations is proposed. By introducing a dielectric tensor ε with enlarged permittivity elements ε_{∗} » ε_{0} to Poisson equation, ∇ ⋅ (ε∇φ) = −ρ (ε_{0} is the permittivity of free space, φ is electrostatic potential and ρ is charge density), the Debye length is artificially elongated and the large-scale system can be numerically treated even for including the self-consistent electron dynamics [T. Takizuka et al., Plasma Fusion Res. 13, 1203088 (2018)]. In cylindrical coordinates (R, θ, Z) for three-dimensional tokamak simulations, a toroidal element ε_{θθ} is chosen much larger than poloidal elements ε_{RR} = ε_{ZZ} = ε_{∗}, and a toroidal mesh size Δ_{θ} can be set much larger than poloidal mesh sizes Δ_{R,Z}. Resultantly the total mesh number becomes reasonably small and computation cost can be reduced. EM responses are also simulated using a modified Darwin model for Ampere's law, ∇^{2}A = −μ_{0}(J − ε∂∇φ/∂t) (A is magnetic vector potential, J is current density, and μ_{0} is the permeability of free space), where light-speed EM waves are neglected. This modification is consistent with the charge-density continuity.

### Keywords

electromagnetic simulation, global plasma, electron dynamics, Poisson equation, Darwin model

### Full Text

### References

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