Design and development of miniaturized epoxy-based colloid emitters and solid-state ion-emitters

Abstract

In this work the development and investigation of two different concepts of miniaturized electrostatic propulsion methods are discussed.In order to fulfill the propulsion-related challenges emerging with a growing number of nano- and microsatellites and high-precision research missions, propulsion systems have to be miniaturized to enable lower system masses, thrust and impulse-bit ranges. Common thruster types with respect to miniaturization prospects and propellant-massefficiency were evaluated and state-of-the-art miniaturized propulsion systems (including propellant and thruster mass, packaging and power processing costs) were reviewed to study their working range in terms of satellite mass. As common propulsion systems cannot be down-scaled forever, modern techniques and novel scalable concepts going beyond established schemes have to be employed.The first part of this work treats the development and design of miniaturized colloid emitters as such emitters become more efficient when miniaturized.The colloid emitters studied in this work were mainly made out of the photo resist SU-8, which is well-established in the microfabrication field as a photoresist allowing one to prepare robust microstructures with a high aspect ratio. The ionic liquid EMI-BF4 was chosen as propellant, which enables the operation of a 1colloid emitter in bipolar mode no additional neutralizer is required. The wetting behavior of EMI-BF4 on SU-8 was investigated and varied by applying different surface treatments. Sample emitters were fabricated and extraction tests were conducted.In the second part of this work a novel electrostatic emitter concept with an alternative approach for generating charged particles is proposed and investigated the solid-state ion-emitter (SSIE).The fabrication and investigation of thin solid-electrolyte membranes were conducted in this work. In particular, the influence of lateral membrane dimensions on the stability of such ion conductor membranes was investigated. The residual stress in YSZ thin-film membranes and the resulting strain patterns were analyzed using Raman spectroscopy.