Low-Cost Optical and Image-Based Analysis of Electrospray System Deposition Pattern for Early-Stage Design

Electrospray thrusters generate charged droplets or ions from ionic liquids and are promising candidates for micro- and nanosatellite propulsion. A major lifetime-limiting factor is overspray, which occurs when wide plume angles or misaligned emissions lead to impingement on extractor electrodes. Understanding plume morphology is therefore essential, yet existing diagnostic techniques often rely on complex or costly angle-resolved setups. This work presents a rapid, low-cost, and easily replicable diagnostic method based on direct imaging of the deposition pattern formed on a planar collector, adaptable to different geometries and operating conditions. Demonstration on a simplified setup shows that, from a single image, the method extracts key parameters, including pattern width, emitter-pattern centroid offset and an 95% of radius distribution (r₉₅) based estimation of angular divergence, with good repeatability (coefficient of variance for area and r₉₅ between 3–7%, centroid variations