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Center for Nonlinear Studies |
The two-fluid plasma model is studied and compared to the asymptotic model, Hall-MHD. Two-fluid effects become significant when the characteristic spatial scales are on the order of the ion skin depth and the characteristic time scales are on the order of the inverse ion cyclotron frequency. In regimes where two-fluid physics is significant, it is necessary to account for the Hall term and the diamagnetic drift term that are missed in ideal- and resistive-MHD. Hall-MHD, which is becoming more common among plasma physicists studying fluid models of plasmas, is compared to the full two-fluid plasma model for the physics that is captured as well as the computational effort. Artificially increasing the electron-to-ion mass ratio in the twofluid plasma model captures all the Hall-MHD physics while using less computational effort. Likewise, artificially decreasing the ratio of the speed of light to the Alfven speed in the two-fluid plasma model also captures Hall-MHD with less computational effort. The two-fluid model provides the solution obtained by Hall-MHD using less computational effort and without the need for artificial dissipation when using an explicit finite element method. Exploring several time integration schemes with the discontinuous Galerkin method for both plasma models is a part of this project. Simulations of the electro-magnetic plasma shock, collisionless magnetic reconnection, axisymmetric Zpinch and field reversed configuration are explored and the results are compared between the models.
Host: Xianzhu Tang, T-5