Conference paper

Design and fabrication of an integrated MEMS-based colloid micropropulsion system

The design, microfabrication and initial performance results of a prototype electrospray thruster with integrated individual extractor electrodes are reported in this paper. The aim was to demonstrate increased thrust with an array of emitters spraying simultaneously. Micromachining technologies were employed to achieve large emitter density per surface area, simple integration and good structural repeatability. The novelty of this work lies in the combination of high aspect ratio capillary emitters (height of 70 microns, inner diameter of 20 microns) with individual extractor electrodes having diameters from 80 microns upwards and a spacing as low as 25 microns from the capillary tips. The individual integrated electrodes, as opposed to the standard approach of one common electrode, allow for greater uniformity in critical voltages between capillaries and more finely modulated thrust control. Tests with the newly developed thrusters using the ionic liquid EMI-BF4 show that starting voltages below 700V and currents around 300nA per emitter can be achieved.

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