Fabrication and characterization of a fully conventionally machined, high-performance porous-media electrospray thruster

TLDR

Electrospray devices have long been used in various applications, and recent research in electric propulsion has advanced their understanding, yet most work has focused on capillary-based droplet emitters, leaving ion-emitting porous-media devices underdeveloped. This work presents fabrication methods and characterization of a fully conventionally machined high-performance porous‑media electrospray thruster, aiming to explore its performance capabilities and enable rapid development using readily available techniques. The thruster comprises 576 emitters machined from porous borosilicate glass, with detailed design and fabrication steps described. It operates stably up to ±700 µA, delivers measurable thrust with characterized I–V curves and ion angular, spatial, mass, and energy distributions, and compares favorably to other devices reported in the literature.

Abstract

Abstract While electrospray devices have been used in a variety of applications for decades, they have recently seen a surge in research within the field of electric propulsion. These research efforts have helped significantly improve the understanding of electrospray thruster operation and optimization, however they have primarily been focused on capillary-based, droplet emitting devices due to the more readily available manufacturing techniques. In contrast, ion emitting, porous-media-based electrospray devices are less developed both theoretically and experimentally. Presented here are fabrication methods and thruster characterization results for an entirely conventionally machined, high performance porous-media electrospray thruster. The goal of this work was to explore the performance capabilities of an ion-mode electrospray thruster which could be fabricated and tested rapidly using techniques readily available to virtually any institution, with the hope of enabling more academic and industrial development of this technology. The thruster described here consisted of 576 emitters conventionally machined out of porous borosilicate glass and is able to maintain stable operation up to ± 700 µ A of emitted ion current. The overall thruster design is described, and detailed fabrication steps are presented for this device. Additionally, performance characteristics are discussed for both positive and negative ion emission, including I–V curves and direct thrust measurements, as well as measurements of the emitted ion angular, 2D spatial, mass, and energy distributions. Examples of the performance of this device compared to other devices found in the literature are also discussed.