A Fluid-kinetic Hybrid Electron Model for Electromagnetic Simulations

A fluid-kinetic hybrid electron model for electromagnetic simulations of finite-beta plasmas is developed based on an expansion of the electron response using the electron-ion mass ratio as a small parameter (Here beta is the ratio of plasma pressure to magnetic pressure.) The model accurately recovers low-frequency plasma dielectric responses and faithfully preserves nonlinear kinetic effects (e.g., phase space trapping). Maximum numerical efficiency is achieved by overcoming the electron Courant condition and suppressing high-frequency modes. This method is most useful for nonlinear kinetic (particle-in-cell or Vlasov) simulations of electromagnetic microturbulence and Alfvenic instabilities in magnetized plasmas