Characterization of an ionic liquid electrospray thruster with a porous ceramic emitter

Molecular dynamics (MD) simulations were performed for ion extraction from electrospray thrusters to investigate relevant extraction processes numerically. To approximate the electrospray jet tip, a simulation domain consisting of 4-5 nm-sized ionic liquid droplets was used. The extracted ion angles and kinetic energies from EMI–BF4 (1-ethyl-3-methylimidazolium tetrafluoroborate) and EMI–Im (1-ethyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide) droplets were quantified by applying uniform electric fields of 1.3–1.7 V nm−1. The MD simulations are in great agreement with simulations presented in the literature and consistently show a greater preference for monomer emission than reported experimentally. At field strengths above 1.5 V nm−1, apparent droplet fracturing and breakup lead to an increase in ion angular velocity distributions. Greater mobility of EMI–BF4 ions than EMI–Im was also observed, indicative of the crucial role of cation-anion hydrogen bond strengths in ion extraction and beam composition between different propellants.

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“…The same trend is given in Fig. 9 for EMI + -[EMI-BF 4 ] based on experimental results by Natisin et al [65] and Chen et al [66].…”

Section: Resultssupporting

confidence: 81%

Molecular Dynamics Simulations of Ion Extraction from Nanodroplets for Ionic Liquid Electrospray Thrusters

et al. 2022

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“…The structural parameters of the electrospray model referred to the actual ILET or the scale of the principle prototype of each research unit [13,14,18,19]. Capillary tubes with an inner diameter of 60 μm, 110 μm and 160 μm were selected as the emitter.…”

Section: Experimental Systemmentioning

confidence: 99%

“…The basic model of an electrospray system consists of emitter (anode), extraction electrode (cathode), propellant, and supply system. A typical electrospray thruster has a pole spacing of less than 5 mm and an emitter size of 10 to 500 μm [13][14][15][16][17]. Therefore, the characteristics of an electrospray system operating in a strong electric field and its structural features constitute the basic models of short-gap low-pressure gas discharge and vacuum discharge under a non-uniform electric field.…”

Section: Experimental Systemmentioning

confidence: 99%

The interelectrode breakdown mechanism and discharge characteristics of the electrospray thruster

Han,

Ye,

Cui

et al. 2024

J. Phys.: Conf. Ser.

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In the actual working process of electric thrusters based on high-voltage electric fields, the discharge breakdown phenomenon is universal and complex, and such phenomena will have a significant impact on the thruster structure, working state and spacecraft system. In order to study the interpolar discharge breakdown characteristics of ionic liquid electrospray thrusters, a basic electrospray model and test system were constructed, and the change curves of discharge characteristic parameters such as breakdown voltage, threshold current, breakdown voltage frequency and so on in the range of 7×10−3~105 Pa with air pressure and transmitter inner diameter were obtained, and the air pressure range that the electrospray model could work in normally was calibrated. The results show that the breakdown voltage characteristic curve of the electrospray model has typical minimum characteristics, and the minimum values all appear around 80 Pa. Lowering the air pressure below 10−2 Pa can effectively increase the breakdown threshold between the poles and the emission current, thereby obtaining a larger voltage regulation range, and when the air pressure is reduced to 7×10−3 Pa, the breakdown can reach more than 3200 V. The 60-μm inner diameter emitter performed better in the discharge experiment, and the breakdown threshold, emission current and operating area range were better than the slightly larger inner diameter emitter under the same working conditions.

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“…In this section, the wedge geometry of emitters will be considered. This geometry is less popular than the cone geometry, but has seen implementation in both research groups (Bretti, 2020;Chen, Chen, & Zhou, 2020; and industry (Demmons et al, 2019). In contrast to cone-shaped emitters, wedge-shaped emitters have a linear extraction surface where the applied electric field is strong and ideally uniform.…”

Section: Wedge Geometrymentioning

confidence: 99%

“…Chen et al recently constructed a wedge-shaped porous emitter capable of up to 500 µA (Chen et al, 2020). The device uses EMI-BF4 as a working fluid, with properties as previously described.…”

Section: Wedge Emitter IImentioning

confidence: 99%

Transient Flow in Porous Electrosprays

Wright

Wirz

2022

Preprint

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Porous ionic electrospray emitters have received significant interest for space propulsion due to their performance and operational simplicity. We have developed a diffusion equation for describing the transient flow response in a porous electrospray emitter, which allows for the prediction of the settling time for flow in the porous emitter. This equation accounts for both the change in liquid storage at exposed pores on the emitter with pressure, and viscous diffusion through Darcy's law. Transient flow solutions are provided for the most common emitter topologies: pillar, cone, and wedge. Transient flow solutions describe the settling time and magnitude of current overshoot from porous electrosprays. Comparing diffusion of pressure to the onset delay model for electrospray emission shows that diffusion is most relevant at higher voltages and when a porous reservoir is used. Accounting for multiple emission sites on the wedge geometry shows that emission sites settle in proportion to emission site spacing to the power -1.74. Applying the diffusion equation to published results shows good agreement between analytical predictions and experimental data.

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Characterization of an ionic liquid electrospray thruster with a porous ceramic emitter

Cited by 23 publications

References 25 publications

Molecular Dynamics Simulations of Ion Extraction from Nanodroplets for Ionic Liquid Electrospray Thrusters

Molecular Dynamics Simulations of Ion Extraction from Nanodroplets for Ionic Liquid Electrospray Thrusters

The interelectrode breakdown mechanism and discharge characteristics of the electrospray thruster

Transient Flow in Porous Electrosprays

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