Lifetime Considerations and Estimation for Electrospray Thrusters

Thuppul, Anirudh; Wright, Peter; Wirz, Richard E.

doi:10.2514/6.2018-4652

Cited by 13 publications

(8 citation statements)

References 8 publications

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“…Electrospray thrusters suffer shortened operating lifetimes due to impingement of ionised propellant onto the extractor and accelerator grids. The high voltages required, results in electrochemical degradation [40,41]. Lifetime can be improved by alternating the emission polarity of the thruster head [42], lowering the propellant flow rate [43] and reducing the conductivity.…”

Section: Electrospray Thrustersmentioning

confidence: 99%

Electric Propulsion Methods for Small Satellites: A Review

2021

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Over 2500 active satellites are in orbit as of October 2020, with an increase of ~1000 smallsats in the past two years. Since 2012, over 1700 smallsats have been launched into orbit. It is projected that by 2025, there will be 1000 smallsats launched per year. Currently, these satellites do not have sufficient delta v capabilities for missions beyond Earth orbit. They are confined to their pre-selected orbit and in most cases, they cannot avoid collisions. Propulsion systems on smallsats provide orbital manoeuvring, station keeping, collision avoidance and safer de-orbit strategies. In return, this enables longer duration, higher functionality missions beyond Earth orbit. This article has reviewed electrostatic, electrothermal and electromagnetic propulsion methods based on state of the art research and the current knowledge base. Performance metrics by which these space propulsion systems can be evaluated are presented. The article outlines some of the existing limitations and shortcomings of current electric propulsion thruster systems and technologies. Moreover, the discussion contributes to the discourse by identifying potential research avenues to improve and advance electric propulsion systems for smallsats. The article has placed emphasis on space propulsion systems that are electric and enable interplanetary missions, while alternative approaches to propulsion have also received attention in the text, including light sails and nuclear electric propulsion amongst others.

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Section: Electrospray Thrustersmentioning

confidence: 99%

Electric Propulsion Methods for Small Satellites: A Review

2021

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“…The primary ∆V limitation of electrospray thrusters is their operational lifetime. Models as well as experimental techniques to analyze various lifetime limitations are developed in [20] and [21]. For iEPS thrusters, the two main life-limiting mechanisms are propellant accumulation on the extractor grid as well as arcing between isolated tips on the emitter array and the extractor grid.…”

Section: Propulsionmentioning

confidence: 99%

Feasibility of a Deep-Space CubeSat Mission with a Stage-Based Electrospray Propulsion System

Jia-Richards

Lozano

Sternberg

et al. 2020

2020 IEEE Aerospace Conference

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Independent deep-space exploration with CubeSats, where the spacecraft independently propels itself from Earth orbit to deep-space, is currently not possible due to the lack of high-∆V propulsion systems compatible with the small form factor. The ion Electrospray Propulsion System (iEPS) under development at the Massachusetts Institute of Technology's Space Propulsion Laboratory is a promising technology due to its inherently small size and high efficiency. However, current electrospray thrusters have demonstrated lifetimes (500 hours) below the required firing time for an electrospray-thrusterpropelled CubeSat to escape from Earth starting from geostationary orbit (8000 hours). To bypass this lifetime limitation, a stage-based approach, analogous to launch vehicle staging, is proposed where the propulsion system consists of a series of electrospray thruster arrays and fuel tanks. As each array reaches its lifetime limit, the thrusters and fuel tanks are ejected from the spacecraft exposing a new array to continue the mission. This work addresses the technical feasibility of a spacecraft with a stage-based electrospray propulsion system for a mission from geostationary orbit to near-Earth asteroid 2010 UE51 through a NASA Jet Propulsion Laboratory Team Xc concurrent design center study. Specific goals of the study were to analyze availability of CubeSat power systems that could support the propulsion system and any other avionics as well as requirements for attitude control and communication between the spacecraft and Earth. Two bounding cases, each defined by the maturity of the iEPS thrusters, were considered. The first case used the current demonstrated performance metrics of iEPS on a 12U CubeSat bus while the second case considered expected near-term increases in iEPS performance metrics on a 6U CubeSat bus. A high-level overview of the main subsystems of the CubeSat design options is presented, with a particular focus on the propulsion, power, attitude control, and communication systems, as they are the primary drivers for enabling the stagebased iEPS CubeSat architecture.

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“…Electron backstreaming analysis showed that increasing the aperture radius produces a significant increase in backstreaming current compared to changing grid spacing; however, reasonably high accelerator grid bias voltages can minimize backstreaming current to negligible amounts for a wide range of acceptable geometries and electron temperatures. Previously presented efforts towards these objectives have been expanded to include more comprehensive thrust and lifetime discussion and calculations, consideration of non-Gaussian plume profiles, and an analytical estimation of space charge effects on electron backstreaming [13].…”

Section: Introductionmentioning

confidence: 99%

Lifetime Considerations for Electrospray Thrusters

Thuppul¹,

Wright²,

Collins³

et al. 2020

Aerospace

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Ionic liquid electrospray thrusters are capable of producing microNewton precision thrust at a high thrust–power ratio but have yet to demonstrate lifetimes that are suitable for most missions. Accumulation of propellant on the extractor and accelerator grids is thought to be the most significant life-limiting mechanism. In this study, we developed a life model to examine the effects of design features, operating conditions, and emission properties on the porous accelerator grid saturation time of a thruster operating in droplet emission mode. Characterizing a range of geometries and operating conditions revealed that modifying grid aperture radius and grid spacing by 3–7% can significantly improve thruster lifetime by 200–400%, though a need for explicit mass flux measurement was highlighted. Tolerance analysis showed that misalignment can result in 20–50% lifetime reduction. In addition, examining the impact of electron backstreaming showed that increasing aperture radius produces a significant increase in backstreaming current compared to changing grid spacing. A study of accelerator grid bias voltages revealed that applying a reasonably strong accelerator grid potential (in the order of a kV) can minimize backstreaming current to negligible levels for a range of geometries.

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Lifetime Considerations and Estimation for Electrospray Thrusters

Cited by 13 publications

References 8 publications

Electric Propulsion Methods for Small Satellites: A Review

Electric Propulsion Methods for Small Satellites: A Review

Feasibility of a Deep-Space CubeSat Mission with a Stage-Based Electrospray Propulsion System

Lifetime Considerations for Electrospray Thrusters

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