Assessing the Efficacy of Two-Fluid Plasma Model and Magnetohydrodynamic Model in Simulating Resistive Drift Instability in Fusion Plasmas: A Comparative Study

The equivalence between a two-fluid plasma mathematical model and an extended-MHD mathematical model for resistive drift-Alfven (RDA) mode is analyzed by deriving local dispersion relations in a nonuniform magnetized plasma. Our results indicate that when it comes to treating the electromagnetic drift mode, the “two-fluid” model is comparable to the “extended-MHD” model. However, due to self-consistent predominant physical effects, there are differences in the results between the two models. Dominant physical effects (such as dynamics of micro mode, resistivity, and propagation of magnetic field perturbation) associated with the two models have been identified. It is found that the two-fluid effect is more prominent compared to that in the “extended-MHD” mathematical model due to an additional term associated with ion polarization drift. However, the “extended-MHD” model has the advantage of being able to characterize the entire MHD wave dynamics on analytical grounds.