Cisquella-Serra Albert, Galobardes-Esteban Marc, Gamero-Castaño Manuel
Department of Mechanical and Aerospace Engineering, University of California, Irvine, California 92617, United States.
ACS Appl Mater Interfaces. 2022 Sep 28;14(38):43527-43537. doi: 10.1021/acsami.2c12716. Epub 2022 Sep 16.
The recent proliferation of SmallSats and their use in increasingly demanding applications require the development of onboard electric propulsion compatible with the power, mass, and volume constraints of these spacecraft. Electrospray propulsion is a promising technology for SmallSats due to its unique high efficiency and scalability across the wide power range of these platforms, for example, from a few watts available in a CubeSat to a few hundred watts in a MiniSat. The implementation of electrospray propulsion requires the use of microfabrication techniques to create compact arrays of thousands of electrospray emitters. This article demonstrates the microfabrication of multi-emitter electrospray sources of a scalable size for electrospray propulsion. In particular, a microfabrication and assembly process is developed and demonstrated by fabricating sources with arrays of 1, 64, and 256 emitters. The electrospray sources are tested in a relevant environment for space propulsion (inside a vacuum chamber), exhibiting excellent propulsive performance (e.g., absence of beam impingement in the extractor electrode, absence of hysteresis in the beam current versus propellant flow rate characteristic, proper operation in the cone-jet electrospraying mode, etc.) and nearly coincident output per emitter. Several design elements contribute to this performance: the even distribution of the propellant among all emitters made possible by the implementation of a network of microfluidic channels in the backside of the emitter array; the small dead volume of the network of microfluidic channels; the accurate alignment between the emitters and extractor orifices; and the use of a pipe-flow configuration to drive the propellant through closed conduits, which protects the propellant.
近年来，小卫星数量激增，且其应用需求日益复杂，这就需要开发与这些航天器的功率、质量和体积限制相兼容的机载电推进系统。电喷雾推进技术因其独特的高效率以及在这些平台广泛功率范围内（例如，从立方星可用的几瓦到微型卫星的几百瓦）的可扩展性，成为小卫星领域一项很有前景的技术。电喷雾推进系统的实现需要使用微加工技术来制造由数千个电喷雾发射器组成的紧凑阵列。本文展示了用于电喷雾推进的可扩展尺寸的多发射器电喷雾源的微加工过程。具体而言，通过制造具有1个、64个和256个发射器阵列的源，开发并展示了一种微加工和组装工艺。这些电喷雾源在与空间推进相关的环境（真空室内）中进行了测试，展现出优异的推进性能（例如，引出电极中无束流撞击、束流电流与推进剂流速特性中无滞后现象、在锥射流电喷雾模式下正常运行等），并且每个发射器的输出几乎一致。有几个设计要素促成了这种性能：通过在发射器阵列背面实施微流体通道网络，使推进剂在所有发射器之间均匀分布；微流体通道网络的死体积小；发射器与引出孔之间的精确对准；以及使用管流配置通过封闭管道驱动推进剂，从而保护推进剂。
