Collector and source sheaths of a finite ion temperature plasma

The region between a Maxwellian plasma source and an absorbing surface is described theoretically with a static, kinetic plasma--sheath model and modeled numerically with a dynamic, electrostatic particle simulation. In the kinetic theory, Poisson's equation and Vlasov equations govern the non-Maxwellian velocity distribution of the ions and electrons. The results in this paper for collector potential and plasma transport agree with the bounded model of Emmert et al. [Phys. Fluids 23, 803 (1980)]. However, this approach differs from those using traditional Bohm sheath analysis by ±0.25 (in units of electron temperature) for potential drop through the collector sheath of a hydrogen plasma. In both the theory and simulation, the plasma source injects equal fluxes of ions and electrons with half-Maxwellian velocities and various mass and temperature ratios and is assumed to have a zero electric field. The potential change within a spatially distributed, full Maxwellian source region is represented with the source sheath potential drop that depends primarily on temperature ratio. This source sheath evolves over a few Debye lengths from the source to neutralize the injected plasma. The plasma flows to an electrically floating collector where the more familiar electron-repelling collector sheath appears. The collector potential ψC and source sheath potential drop ψP (in units of electron temperature) are evaluated as a function of mass and temperature ratio. The velocity moments of density, drift velocity, temperature, kinetic energy flux, and heat flux are also derived as a function of ψC and ψP. Comparisons with electrostatic particle simulations are shown for the ion/electron mass ratios of 40 and 100 and temperature ratios of 0.1, 1, and 10