Plasma Sheath Around Long Conductors with Elliptic Cross-sections

The plasma sheath around an emissive surface immersed in a plasma is a topic of interest for a wide range of applications like emissive probes, electrodynamic tethers, and dusty plasma. This work presents a Vlasov-Poisson solver to study the plasma structure around a long body with an elliptic cross-section. Since angular momentum is not conserved by particle trajectories, the code allows to extend the orbital motion theory to non-integrable configurations. Some subtle physical and numerical features are highlighted, including the filamentation of the distribution function and its fractal structure in velocity space. A parametric analysis varying the probe eccentricity and the emission level is presented. Relevant features and macroscopic magnitudes, like density and potential profiles, and collected and emitted current are shown. Orbital-motion-limited and space-charge-limited regime transitions are both investigated. The stationary nature of the model and its implications in the development of reliable stationary Vlasov-Poisson solvers are discussed.

This work was supported by the European Union's Horizon 2020 Research and Innovation Programme under Grant agreement No 828902 (E.T.PACK project). GSA work is supported by the Ministerio de Ciencia, Innovacion of Spain under the Grant RYC-2014-15357.