Research and development of a charged-particle bipolar thruster.

Mahoney, John F.; Moore, R.; Perel, Julius; Yahiku, A. Y.

doi:10.2514/3.5137

Cited by 48 publications

(22 citation statements)

References 1 publication

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“…The PIR has been primarily based on electrosprays of liquid metals, 3,4 often employed as bright sources of ions in propulsion. 5 However, emissions dominated by small ions have also been observed from nonmetallic purely ionic substances, initially sulfuric acid, 6 and more recently room temperature molten salts referred to as ionic liquids ͑ILs͒. 7 As in liquid metal ion sources ͑LMISs͒, ionic liquid ion sources ͑ILIS͒ were initially based on delivery of the electrosprayed liquid to the sharpened tip of an electrified capillary through the bore of the capillary.…”

Section: Introductionmentioning

confidence: 99%

Effect of tip curvature on ionic emissions from Taylor cones of ionic liquids from externally wetted tungsten tips

Castro

Mora

2009

Journal of Applied Physics

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Several ionic liquids (ILs) of relatively high electrical conductivity (K) and surface tension (γ) are electrosprayed under vacuum from electrochemically sharpened and roughened tungsten wires with tip radii R varying from 2 to 80 μm. All our tips exhibit a purely ionic emission, confirming the versatility of these ionic liquid ion sources (ILIS) previously demonstrated by Lozano and Martínez-Sánchez using R∼20 μm. A drastic increase in ion current from 50 to 1000 nA results when increasing R from 2.5 up to 29 μm and above, offsetting the considerable disadvantage in current emission level previously observed for ILIS (∼200 nA) versus conventional internally fed capillary tube emitters (∼1000 nA). Experiments with shielding electrodes show that this increase in current is not due to a reduction in space charge effects associated to the higher onset voltages required at smaller curvatures. It results from a reduction in flow impedance at increasing R. Long-term stable Taylor cone operation was not achieved with any of the ILs tested, even when alternating the tip voltage to minimize electrochemical reactions.

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Section: Introductionmentioning

confidence: 99%

Effect of tip curvature on ionic emissions from Taylor cones of ionic liquids from externally wetted tungsten tips

Castro

Mora

2009

Journal of Applied Physics

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“…1). Aside from liquid metals [3], concentrated aqueous acids [22], and ILs [23,24] are among a very limited number of liquids known to support this unique mode of electrohydrodynamic charge emission.…”

Section: Introductionmentioning

confidence: 99%

“…The seminal work of Perel et al in the late 1960s established, for the first time, the viability of the pure ion mode with nonmetallic liquids [22]. This work leveraged concentrated solutions of sulfuric acid but received little follow-up until the early 2000s when Romero-Sanz and colleagues extended the finding to ILs [23].…”

Section: Introductionmentioning

confidence: 99%

Electrohydrodynamics of an ionic liquid meniscus during evaporation of ions in a regime of high electric field

2019

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Numerical investigations are presented for an ionic liquid meniscus undergoing evaporation of ions in a regime of high electric field. A detailed model is developed to simulate the behavior of a stationary meniscus attached to a liquid feed system. The latter serves as a proxy for commonly utilized electrospray emitters such as needles and capillary tubes. Two solution families are identified for prototype liquid analogous to the ionic liquid 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4). The first belongs to a regime of low electric field in which the meniscus is blunt and does not emit charge. The second belongs to a regime of high electric field in which a conelike meniscus produces charge from a sharp tip. Electrohydrodynamic features of the meniscus in this regime are presented. These reveal that the meniscus is Stokesian and hydrostatic and governed by conduction. The applied electric field influences both the shape of the meniscus and the current that it produces while the impedance of the feed system-which must be above a threshold value in order to ensure that the current, and therefore the flow, remains below a maximum value-influences the meniscus current but not the macroscopic shape. In general, this shape deviates from Taylor's idealized cone.

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“…1-3 The unique features motivate the interests of many technical fields, such as thin film and nanomaterial preparations, 4,5 space vehicle propulsions, 6 insecticide spray, 7 drug delivery, 8 and so on. Because the droplets generated by electrospray are advanced in high bulk charge to mass ratio, it is applied in mass spectrometry 9 as well.…”

Section: Introductionmentioning

confidence: 99%

Spraying modes in coaxial jet electrospray with outer driving liquid

et al. 2005

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Coaxial jet electrospray is a technique to generate microencapsules, which uses electric forces to create a coaxial microjet from two immiscible liquids. Compound droplets with narrow size distribution are produced after the jet breaks up. In this paper, the spraying modes are investigated experimentally with proper flow rates of the inner and outer liquids. Ethanol/glycerol/tween mixture ͑outer liquid͒ and cooking oil ͑inner liquid͒ are fed into the gap between outer and inner capillaries and the inner capillary, respectively. The spraying modes presented in our experiments are "dripping mode," "dripping mode in spindle," "cone-jet mode," "pulse mode in cone," and "multijets mode" sequentially, as the applied voltage increases. The region of stable cone-jet mode extends with decrease of the outer liquid flow rate and increase of the inner one. It is found that the spray phenomena are mainly determined by properties of the outer liquid, which is viscous and electric conductive enough. A rudimentary physical model is developed, in which both the viscosity and liquid interface tension are taken into account.

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Research and development of a charged-particle bipolar thruster.

Cited by 48 publications

References 1 publication

Effect of tip curvature on ionic emissions from Taylor cones of ionic liquids from externally wetted tungsten tips

Effect of tip curvature on ionic emissions from Taylor cones of ionic liquids from externally wetted tungsten tips

Electrohydrodynamics of an ionic liquid meniscus during evaporation of ions in a regime of high electric field

Spraying modes in coaxial jet electrospray with outer driving liquid

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