Self-Consistent Hybrid Technique for Modeling Particle Acceleration in Space Plasma Outflow

Plasma outflows exist in various regions in space. For instance, the solar wind is an outflow of plasma along the open magnetic field lines emanating from the sun. In the polar cap region of the Earth, there is the polar wind, which features particle outflow along the open geomagnetic field lines. In the auroral zone, conic velocity distributions of ions are frequently observed as those particles travel upward after being heated in the directions transverse to the magnetic field. The primary physical mechanisms responsible for these phenomena of plasma outflow may be all different. We discuss a self-consistent hybrid modeling technique that is capable of incorporating various kinetic effects in space plasma outflows. The modeling technique is hybrid in that it combines fluid and kinetic calculations. By applying the technique to the polar wind to model the effects of photoelectrons, and to the solar wind to study the effects of ion cyclotron waves, we have demonstrated in both applications that the kinetic effects considered may provide an explanation for the observed qualitative features in the outflow. For the auroral zone, we have used a preliminary model to consider ion energization due to intermittent electric field fluctuations. Our studies have shown that such fluctuations can effectively energize the ions and lead to the formation of ion conics. The degree of ion energization would depend on the intermittency of the electric field. Recent analyses of the auroral zone electric field have shown that such fluctuations are indeed intermittent in nature, suggesting the relevance of our studies for the region. Here, we describe the salient features and utilities of the self-consistent hybrid technique, and discuss how the technique can be applied to take into account the effects of intermittent fluctuations on plasma outflows.