Sheath and presheath in plasma with warm ions

Abstract

Numerical solutions are found for the potential profile of the presheath and sheath in plasma with a Maxwellian ion source distribution. Solutions are obtained for ratios of the electron temperature to ion source temperature from 0.1 to 10 for plasmas that are 20, 50, and 100 Debye lengths from the midplane to the wall. With increasing ion source temperature, the potential profile falls less rapidly in the presheath and the current density of ions to the wall increases and approaches the random ion current calculated for the source temperature. Ion distribution functions at the midplane, the sheath-presheath boundary, and at the wall are found and are more sharply peaked than Maxwellian distributions. At the midplane, the effective ion temperature is much less than the ion source temperature.