Particle charging and lofting from a surface under plasma conditions relevant for space and EUV applications

Particle removal from sensitive surfaces is of great importance in the space and semiconductor industries. To remove particles from surfaces, the force balance between adhesive and repelling forces must be shifted toward a net repelling force. In low-pressure environments, this may be achieved by an electric charge on the particle in combination with an electric field. Particle charging arises from exposure to electric or photon currents, which are conditions prevalent in space environments and Extreme Ultraviolet (EUV)-driven plasmas. Simultaneously, surface charge biasing or a plasma sheath establishes an electric field that exerts a force on the particle. The details of the charging mechanisms remain an active topic of research, and several models have been developed which have been tested experimentally against release probabilities, launch velocities, and inferred charges from force balance analysis. However, due to the poorly constrained nature of adhesive forces, obtaining exact values for particle charge remains difficult. Experimental studies tend to support the Patched Charge Model, establishing it as a promising framework for explaining electrostatic lofting of insulating particles within space and EUV environments. This model is based on the presence of microcavities within the system that accumulate charge locally from the emission of secondary and photoelectrons. Nevertheless, further research is needed to validate these models quantitatively and to develop more predictive tools for controlling particle release from surfaces. This tutorial summarizes charging mechanisms, compares leading models against experimental evidence, and identifies open questions critical to predictive control of electrostatic particle removal in space and EUV environments.