A fluid-ion and particle-electron model for low-frequency plasma instabilities

Abstract

We have developed a hybrid (particle/fluid) computer code for the study of quasi-neutral micro-instabilities for inhomogeneous plasmas that are immersed in a magnetic field. The ions are treated in the fluid approximation, retaining perpendicular E x B and polarization drifts as well as the parallel momentum and ion temperature equations. The electrons are represented as particles with perpendicular E x B drifts and parallel kinetics, thus exactly describing the effects of trapped electrons and electron-wave resonances. The code may be used in the study of low frequency (@w < @WPini, where @Wi = eB/mic) universal mode drift waves, ion-pressure-driven modes, or curvature-driven modes. At present we have implemented an electrostatic, two-dimensional, slab geometry version of the code. The model has been tested extensively for sound-wave propagation, the collisionless (universal mode) drift wave real frequency and growth rate, the @hi-mode real frequency and growth rate, and the fluctuation spectrum has been elucidated. As a nonlinear test case, we have also studied the nonlinear properties of the collisionless drift wave.