A micro-fabricated linear array of electrospray emitters for thruster applications

This paper reports the design, fabrication, and experimental characterization of an internally fed linear array of electrospray emitters intended for space propulsion applications. The engine uses doped formamide as propellant and operates in the single-Taylor-cone droplet emission regime. The engine implements the concept of hydraulic and electrodynamic flow rate matching to achieve electrical control. The engine uses a set of meso-scaled silicon deflection springs to assemble the hydraulics to the electrodes, allowing to decouple the corresponding process flows. The micro-fabrication of the engine is described and novel technologies that were developed are reported. Experimental results that demonstrate cumulative uniform and steady operation are provided. Current-flowrate characteristics of the engine are in agreement with a reduced-order model. Experimental data demonstrating the low divergence of electrospray emitter arrays operated in the single Taylor Cone is in qualitative agreement with a reduced-order mode that assumes the absence of a thermalized tail in the plume.