The Inverted Plasma Sheath, Grant Johnson
Channel: NERSC
Date: 2023-01-06

When an electron emitting surface is in contact with a collisional plasma, a unique regime of plasma sheath may form, an inverse sheath. The inverse sheath regime most notably differs from the classical Debye sheath by having a floating potential above that of the plasma potential. This leads to a restructuring of the plasma flows. The ubiquity of emitting surfaces in laboratory plasmas means there are a number of applications of the inverse sheath such as extending hot cathode lifetimes, cooling of the local plasma, and modifications to emissive probe theory. Due to the collisional nature of the sheath and the trapped population of ions, kinetic simulations are required to answer outstanding questions which remain about the sheath’s formation, and transport properties. To address these questions, we have developed 1D-1V and 2D-2V kinetic continuum codes which include collisions and allows us to explore the inverse sheath in relevant configurations. In this talk I will introduce the fundamentals of the inverse sheath, the codes we have developed to solve these problems, and the applications of the inverse sheath.