Enabling Ultraviolet Lasers for Touchless Spacecraft Potential Sensing

Ultraviolet (UV) lasers are proposed as a replacement for low-energy electron beams in touchless spacecraft potential sensing. Theoretical considerations support their use as photoelectron sources due to their insensitivity to the electrostatic environment, which leads to more robust and controllable systems. The feasibility of this approach is verified in a representative scenario of application, and its relevance for spacecraft charge control and material identification is discussed. A simplified photoemission framework is presented and validated with vacuum chamber experiments by means of particle tracing simulations, showing that such a framework can be used to determine the spatial distribution of photoelectrons emanating from a target surface and an informed estimate of its magnitude. The possibility of combining this method with high-energy electron beams is also discussed as a way to enhance the robustness and accuracy of the sensing process. Ultimately, the analysis supports the use of UV lasers in a wide range of spacecraft charging technologies in geosynchronous orbit and deep space.