3D micro printed capillary electrospray thruster with a fully modular integrated extraction electrode

Abstract

An internally wetted capillary-type electrospray thruster design is presented. The capillary emitters are optimized for fabrication using 3D micro lithography and can achieve sub 10-micrometer capillary diameters with an aspect ratio of over 20. Also provided is a design for a completely modular integrated extraction electrode that comprises an electrode carrier produced by 3D micro lithography and a thin metal film. The electrode orifices, distance to emitters, and size are all customizable thanks to the modularity of the design, which is compatible with any electrospray thruster type. The design provides alignment precision within 5 micrometers of the emitter tip and electrode orifice. While our new electrode achieved reproducible extraction, instability is still present. The data on emission from these emitter-electrode stacks is presented, as well as in situ microscopic optical observation of individual emitters. The images demonstrate emission in multiple extraction modes, microfluidic behaviour of the capillaries in space-like conditions, and interactions of the emission modes with the integrated electrode.