Diamond Cathode Coating for Spacecraft Charge Mitigation

Physical Sciences Inc. (PSI) proposes the development of a composite laminate cathode coating based largely on consumer off the shelf (COTS) industrial materials functionalized to possess a low work function, negative electron affinity surface. The cathode coating is applicable to any surface of a spacecraft, regardless of shape or material, and allows passive one wire operation for spacecraft charge mitigation by utilizing photoelectric and triple point effects. In Phase I of the program, PSI will obtain sample raw materials, functionalize them and coat representative substrates such as aluminum and conductively coated glass. PSI will also develop monolithic devices with properties similar to the laminate coating as a risk mitigation strategy. We will measure samples emission current densities and ignition potentials during discharge in simulated space environments and characterize their surface morphology by optical and electron microscopy. Results of the Phase I emission studies will guide the optimization of the coating technology in Phase II. The primary benefits derived from this technology will be a rugged and simple spacecraft cathode coating that will extend the operational life and safety of US space assets as well as aid in realization of advance spacecraft power and propulsion systems such as the electrodynamic tether.