Charge Neutralization and Direct Thrust Measurements from Bipolar Pairs of Ionic Electrospray Thrusters

Courtney, Daniel G.; Shea, Herbert; Dannenmayer, Käthe; Bulit, Alexandra

doi:10.2514/1.a33863

Cited by 22 publications

(8 citation statements)

References 35 publications

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“…For the pure ionic liquid electrospray thruster, due to its structural size limitation, it is infeasible to use an external neutralizer to achieve the plume neutralization. Generally, there are two operation modes to accomplish the plume neutralization of the pure ionic electrospray thruster: the alternating polarity operation mode and the bipolar operation mode [18]. The alternating polarity operation mode is to alternately change the polarity of the extraction voltage for a single thruster so that the emitted plume contains both positive and negative ions to achieve plume neutralization.…”

Section: Introductionmentioning

confidence: 99%

Plume neutralization of an ionic liquid electrospray thruster: better insights from particle-in-cell modelling

Zhang¹,

Cai²,

He³

et al. 2021

Plasma Sources Sci. Technol.

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Ionic liquid electrospray thrusters with high specific impulse, high thrust accuracy and low thrust noise are very promising for space gravitational wave detection missions. The plume which may lead to surface charging of solar panels and sensitive spacecraft components is a great concern for the applications of electrospray thruster. Therefore, this paper investigates the plume neutralization process of the ionic liquid electrospray thruster through fully kinetic Particleincell simulations. The unipolarity operation mode is firstly simulated and compared with the experimental measurements. The bipolar operation mode is analyzed by considering the premixing and the separation of positive and negative ion beams. At the same time, the effect of beam spacing on the plume characteristics is investigated. The results show that the plume neutralization of the ionic liquid electrospray thruster is achieved by the spatial and temporal oscillations of the ion beams. In the horizontal direction, the spatial oscillations are caused by the different mass and hence velocities of positive and negative ions. In the vertical direction, the spatial oscillations are mainly because of the non-zero beam spacing. The temporal oscillations may be related to the charge separation induced by the different mass and hence velocities of positive and negative ions. As the beam spacing increases, the amplitude of the electric potential oscillations changes scarcely in the horizontal direction while increases in the vertical direction. The ion temperature goes up with the beam spacing and the deviation of the temperature of beam ions does not exceed 15 eV in the horizontal direction but exceeds 100 eV in the vertical direction. Moreover, the plume divergence half angle and the beam spacing are positively correlated, suggesting that the ionic electrospray thrusters with positive and negative polarity need to be placed as close as possible in the spacecraft.

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Section: Introductionmentioning

confidence: 99%

Plume neutralization of an ionic liquid electrospray thruster: better insights from particle-in-cell modelling

Zhang¹,

Cai²,

He³

et al. 2021

Plasma Sources Sci. Technol.

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“…Small satellites are recommended for the building of the next-generation global internet due to specific impulse, precise thrust control, low acoustic noise, low power consumption, and reduced structural mass, making it ideal for small satellites [12][13][14][15]. Additionally, ILET generates bipolar particles and achieves self-neutralization of the plume by directly applying positive or negative high voltage to the emitter without external neutralizers [16][17][18]. For small satellites with limited resources, these features significantly reduce the volume, mass, and power requirements of the propulsion system.…”

Section: Introductionmentioning

confidence: 99%

“…In the temporal distribution mode, self-neutralization is achieved by alternating the voltage polarity of an individual thruster, resulting in the plume that contains both cations and anions in space [24][25][26][27]. In the spatial distribution mode, selfneutralization of the plume is achieved by positioning two thrusters side by side with opposite polarities and emitting bipolar ions [9,16]. Researchers have conducted experimental and simulation studies to analyze the characteristics and selfneutralization effectiveness of plumes.…”

Section: Introductionmentioning

confidence: 99%

Study on the plume self-neutralization of ionic liquid electrospray thruster based on median potential

Du,

Wu,

et al. 2024

Plasma Sources Sci. Technol.

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Ionic liquid electrospray thruster (ILET) has the advantages of high specific impulse, precise thrust control, and low structural mass, which make it ideal for small satellites. The charged particles of ILET’s plume may lead to device charging or even damage, restricting its engineering applications. Thus, this paper examines the self-neutralization effectiveness of the ILET's plume under various emission conditions using particle-in-cell simulations. In order to accurately evaluate the self-neutralization effectiveness of the ILET’s plume, the median potential is explained in this paper and its reasonableness as the evaluation criterion for self-neutralization of the plume is verified. The working envelope for achieving self-neutralization of the ILET’s plume is determined by simulating the bipolar plume under various emission conditions. The results indicate that when the highest and lowest potentials are the same, the mean electric field strength between two points in space with a better degree of neutrality is 200% higher compared to points with a lesser degree of neutrality. The study determines the working envelope to realize self-neutralization of the ILET’s plume with an effectiveness of 70%. When the emission voltage of the anode thruster is fixed, the range of the cathode thruster’s voltage ranges from 108.36 V to 228.74 V. The asymmetry between the anode and cathode emissions of the ILET prototype significantly influences the operational range of the cathode thruster. Greater asymmetry leads to a narrower operating range for the ILET to achieve self-neutralization of the plume. This study serves as a guide for the ILET to achieve self-neutralization of the plume.

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“…Thus, it is more feasible to study the meniscus formation process by means of simulation. Besides, the ILETs can emit either positive or negative particles by alternating the voltage polarity of the emitter, and this property is significant in the suppression of electrochemical reactions and neutralization of the plume [26,27]. However, the transient response during the voltage polarity alternation of the ILETs has not been studied.…”

Section: Introductionmentioning

confidence: 99%

Simulation of liquid meniscus formation in the ionic liquid electrospray process

Liu¹,

Deng²,

Sun³

et al. 2022

Plasma Sci. Technol.

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Ionic liquid electrospray thrusters (ILETs) have advantages of high specific impulse, compact structure and low power, which are excellent candidates for the propulsion system of nanosatellites. Electrospray is the working principle of ILETs. Though tremendous efforts have been made to investigate electrospray, some aspects, such as the evolution of the menisci on the micropores of porous emitter tips and the transient response of the meniscus during the polarity alternation, need to be further understood. This paper presents a computation fluid dynamics (CFD) model to describe the meniscus formation in the ionic liquid electrospray process. The CFD model, based on the Taylor-Melcher leaky dielectric fluid theory and the volume of fluid (VOF) method, is validated by experiments. The evolution of the meniscus on the basis of a micropore is presented using two typical ionic liquids, EMI-BF4 and EMI-Im. The influences of the pore size, flow rate and applied voltage on the formation of the meniscus have been studied. Results show that a larger pore is more likely to start emission. And the time consumed for liquid meniscus formation is decreased with the increase of the applied voltage and flow rate. Further, it is found that alternation of polarity does not destroy the structure of the meniscus but retards the formation process. And a faster polarity alteration leads to a shorter delay of meniscus formation time.

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Charge Neutralization and Direct Thrust Measurements from Bipolar Pairs of Ionic Electrospray Thrusters

Cited by 22 publications

References 35 publications

Plume neutralization of an ionic liquid electrospray thruster: better insights from particle-in-cell modelling

Plume neutralization of an ionic liquid electrospray thruster: better insights from particle-in-cell modelling

Study on the plume self-neutralization of ionic liquid electrospray thruster based on median potential

Simulation of liquid meniscus formation in the ionic liquid electrospray process

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