Electrospray Emitter Coatings for Surface Reaction Control
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Solution Overview
Problem
Electrospray devices experience reduced lifetime and performance due to reactions between electrically conductive surfaces and working material, and shorting events between emitter arrays and electrodes lead to degradation and failure.
Innovation Solution
Coating electrically conductive surfaces with dielectrics, using dielectric materials for manufacturing, and employing high impedance resistors to couple electrodes to a ground plane through balancing electronics to mitigate these issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrically conductive surfaces are used in electrospray devices, then electrical conductivity and emitter function are improved, but surface reactions with working material occur reducing lifetime and performance
Solution Approach 1:
A dielectric coating layer is introduced as an intermediary between the electrically conductive surface and the working material. This dielectric layer prevents direct contact and chemical reactions between the conductive surface and working material, while still allowing the electromagnetic field to penetrate and function. The dielectric acts as a protective mediator that maintains electrical functionality without exposing the conductive surface to harmful reactions.
Solution Approach 2:
The emitter structure employs a composite design combining a conductive substrate with a dielectric coating layer. This composite structure integrates the electrical conductivity needed for emitter function with the chemical inertness of the dielectric material, creating a surface that both conducts electricity and resists reactions with working material, thereby extending device lifetime.
2Productivity
If emitter arrays are positioned close to electrodes for efficient ion extraction, then thrust efficiency is improved, but shorting events occur causing degradation and failure
Solution Approach 1:
A dielectric barrier layer is positioned between the emitter array and the electrode to prevent direct electrical contact and shorting events. This intermediary dielectric layer allows the electric field to pass through for efficient ion extraction while physically preventing conductive pathways that would cause shorting, degradation, and failure.
Solution Approach 2:
A thin dielectric film or coating is applied to the electrode surface facing the emitter array. This thin film is sufficient to prevent shorting events while maintaining the electric field strength needed for efficient ion extraction. The thin film acts as a protective barrier without significantly compromising the electromagnetic field penetration required for thrust efficiency.
3Reliability
If dielectric coatings are applied to conductive surfaces to prevent reactions, then device lifetime is improved, but manufacturing complexity increases
Solution Approach 1:
The dielectric coating is designed as a thin, simple layer that can be applied using cost-effective deposition techniques. Rather than requiring complex multi-layer structures or precision engineering, the solution uses a straightforward dielectric coating that provides adequate protection against surface reactions, making the manufacturing process economically viable and relatively simple.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances the lifetime and performance of electrospray devices by reducing the impact of surface reactions and shorting events, maintaining target impulse and thrust while minimizing performance deviations.
Implementation Method 1
Coating electrically conductive surfaces with dielectrics
Implementation Method 2
employing high impedance resistors to couple electrodes to a ground plane through balancing electronics
Implementation Method 3
Electrospray devices experience reduced lifetime and performance due to reactions between electrically conductive surfaces and working material
Data Source
AI summary
An electrospray emitter can include an emitter structure connected to a reservoir containing a working material in electrical communication with a first electrode and an electrode separated from an apex of the emitter structure by a distance, wherein a surface of the grid electrode proximal the emitter structure comprises at least one coating.