The robust MHD code is needed for nuclear fusion experiments such as the pellet injections and/or the gas puff jet. The density (pressure) gradient and/or density (pressure) ratio are very large value (up to 10⁵) in these phenomena. Therefore, the development of the robust MHD code is important for understanding these special MHD behaviors.
The governing equations for one fluid model are as follows,
∂ρ/∂t+∇·ρV=0
∂V/∂t+V·∇V=−∇p⁄ρ + R_pR_mJ×B + R_e⁻¹((∇²V + 1⁄3∇( ∇ ·V))
∂p/∂t=−∇·pV −( γ−1)p∇ ·V +(γ−1)R_p R_mJ² −γ ∇ ·q +(γ−1)Φ
(ρ,p : dimension-less density and pressure, V : dimension-less velocity[vector], R_p: magnetic pressure number, R_m: magnetic Reynolds number, R_e: Reynolds number, q : thermal flux[vector], Φ : dissipation function due to stress)
As well known, these equations are derived from the mass, momentum and energy conservation laws. Using CIP method¹, the program was successfully developed to solve above-mentioned equations, generalized Ohm^,s equation and Maxwell equations.
The test results of the development code for one fluid were very good. The one fluid MHD was successfully simulated with the density ratio of 10⁵. Also, MHD shock simulations using this code were good. We are modifying this MHD code to treat multi-fluids (included in neutral gas) to simulate the pellet injection at very first time.

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