Transient plasma sheath model for thin conductors excited by negative high voltages with application to electrodynamic tethers

The electrodynamic tether is a powerful new tool for in-space propulsion and in situ ionospheric research. To fully exploit its potential, knowledge of both its steady-state and transient electrical responses is needed. The tether's transient response is governed by the interaction of the tether and its endpoints with the surrounding ionospheric plasma. The authors present an improved model of the plasma-tether interaction that accounts for high-induced voltages and a dynamic nonlinear sheath. In this work, the model for the plasma-tether system was developed analytically and verified via particle-in-cell simulations and through experimental data. The model is valid in the temporal regime between the ion and electron plasma periods, and for large negative applied voltages. The model is based on an ion-matrix-sheath that is a function of applied voltage. Although the investigation was geared toward electrodynamic tethers, it also has application to other areas of research that employ the dynamic nature of the plasma sheath.