Electrostatic Lenses for Laboratory Spacecraft Wake Generation

Cislunar spacecraft may be mesothermal with respect to ambient plasma, generating spacecraft ion wakes. It is unknown that how these wake formations impact technologies, such as touchless potential sensing and the electrostatic tractor. Therefore, wakes are generated in the Electrostatic Charging Laboratory for Interactions between Plasma and Spacecraft (ECLIPS) vacuum chamber at the University of Colorado at Boulder to determine how to account for and take advantage of the wake formations. The natural ion beam generated in the chamber is too small to place a several centimeter-sized objects in the wake and expands radially outward. To correct this, electrostatic lens configurations are designed to expand and refocus the ion beam. Optimization algorithms are used to determine the ideal electrostatic lens configuration, and the design, installation, and characterization of these lenses are presented. The experimental and numerical simulations show good agreement, enabling the installation of simple electrostatic lenses for ion beam manipulation in vacuum systems. Representative cislunar spacecraft wakes are then successfully generated and measured in the ECLIPS vacuum chamber.