Global Hybrid Simulations: Nuts and Bolts

Traditionally global MHD simulations have been used to model the global dynamics of the magnetosphere while hybrid (electron fluid, kinetic ions) simulations have been applied to examine the physics of local boundaries and discontinuities. However, with improvements in simulation techniques and advances in computer technology it has become possible to extend the hybrid simulation to global scales. The extension of the hybrid paradigm from local to global scales requires specialized treatment as the simple application of this technique can lead to undesirable results and is computationally inefficient. In this presentation, we discuss the technology behind these codes and demonstrate their utility through several examples. Our approach is to use global hybrid simulations as a complementary rather than a replacement tool to global MHD simulations. Comparison and contrast of global MHD and hybrid simulation results performed in the same parameter regime can yield important insight about the underlying physics. We will illustrate this through several examples.