Hybrid Particle/Fluid Modeling of Plasmas

Particle in cell (PIC) methods enjoy great success in modeling devices that include moderately dense plasmas. However, as the plasma density becomes high in a large volume, the number of particles to track becomes computationally prohibitive. Reducing the number of particles by creating larger “macro particles” introduces significant numerical error. Alternatively, highdensity plasmas in large volumes can be modeled using a dielectric fluid description. However, such a description is not accurate for non-Maxwellian energy distributions. Some physical processes, such as air breakdown phenomena, involve high-density plasmas with energy distributions that are partially Maxwellian but include a long, high energy tail. The particles in the high-energy tail are those responsible for the majority of interactions that lead to a qualitative change in physical behavior. Thus, a fluid description that neglects the high-energy tail fails to capture the physics of interest. A hybrid plasma description has the potential to capture the relevant physics in a tractable computational time.