Operational Characteristics of Colloid Thrusters

Perel, Julius; Yahiku, A. Y.; Mahoney, John F.; Daley, Howard L.; Sherman, A.

doi:10.2514/3.59715

Cited by 14 publications

(2 citation statements)

References 4 publications

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“…Further increasing the bias voltage leads to the unstable multi-jet mode, when more than one jet is emitted from the surface of the meniscus; this regime is associated with wide variation in the size of the electrosprayed particles. 35 Most of the data collected in the wet experiments correspond to operation in cone-jet mode; however, Fig. 6a shows an interesting experimental behaviour obtained while investigating single and coaxial electrospray emission of DIW : ISP 1 : 1 v/v solution flowing at 1.0 mL h −1 , using a singleemitter device.…”

Section: Spraying Modesmentioning

confidence: 99%

Additively manufactured MEMS multiplexed coaxial electrospray sources for high-throughput, uniform generation of core–shell microparticles

Olvera-Trejo

Velásquez–García

2016

Lab Chip

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This study reports the first MEMS multiplexed coaxial electrospray sources in the literature. Coaxial electrospraying is a microencapsulation technology based on electrohydrodynamic jetting of two immiscible liquids, which allows precise control with low size variation of the geometry of the core-shell particles it generates, which is of great importance in numerous biomedical and engineering applications, e.g., drug delivery and self-healing composites. By implementing monolithic planar arrays of miniaturized coaxial electrospray emitters that work uniformly in parallel, the throughput of the compound microdroplet source is greatly increased, making the microencapsulation technology compatible with low-cost commercial applications. Miniaturized core-shell particle generators with up to 25 coaxial electrospray emitters (25 emitters cm) were fabricated via stereolithography, which is an additive manufacturing process that can create complex microfluidic devices at a small fraction of the cost per device and fabrication time associated with silicon-based counterparts. The characterization of devices with the same emitter structure but different array sizes demonstrates uniform array operation. Moreover, the data demonstrate that the per-emitter current is approximately proportional to the square root of the flow rate of the driving liquid, and it is independent of the flow rate of the driven liquid, as predicted by the theory. The core/shell diameters and the size distribution of the generated compound microparticles can be modulated by controlling the flow rates fed to the emitters.

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Section: Spraying Modesmentioning

confidence: 99%

Additively manufactured MEMS multiplexed coaxial electrospray sources for high-throughput, uniform generation of core–shell microparticles

Olvera-Trejo

Velásquez–García

2016

Lab Chip

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“…Interest in this phenomenon began to spread and by the early 1960's, V. E. Krohn [5] and co-workers at TRW recognized that the spontaneous process by which an electrified liquid can undergo fission to produce charged droplets and ions could be of enormous relevance to the burgeoning field of electrostatic propulsion [6][7][8][9] and in particular, development of so-called "space thrusters". While other researchers focused on colloid thrusters based on electrospray from dielectric liquids, Krohn instead concentrated on cusp formation in liquid alkali metals.…”

Section: B Experimental Studies By Krohn and Co-workersmentioning

confidence: 99%

Electrified cone formation in perfectly conducting viscous liquids: Self-similar growth irrespective of Reynolds number

Albertson

Troian

2019

Physics of Fluids

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Above a critical field strength, the free surface of an electrified, perfectly conducting viscous liquid, such as a liquid metal, is known to develop an accelerating protrusion resembling a cusp with a conic tip. Field self-enhancement from tip sharpening is reported to generate divergent power law growth in finite time of the forces acting in that region. Previous studies have established that tip sharpening proceeds via a self-similar process in two distinct limits -the Stokes regime at Re = 0 and the inviscid regime Re → ∞. Using finite element simulations to track the acceleration of an electrified protrusion in a perfectly conducting Newtonian liquid in vacuum held at constant capillary number, we demonstrate that the conic tip always undergoes self-similar growth irrespective of Reynolds number. The computed blow up exponents at the tip for the terms in the Navier-Stokes equation and interface normal stress condition reveal the different forces at play as Re increases. Rescaling of the tip shape by the capillary stress exponent yields excellent collapse onto a universal conic tip shape with interior half-angle dependent on the magnitude of the Maxwell stress. The rapid acceleration of the liquid interface also generates a thin surface boundary layer with very high local strain rate. Additional details of the modeled flow, applicable to cone growth in systems such as liquid metal ion sources, help dispel prevailing misconceptions that dynamic cones resemble conventional Taylor cones or that viscous stresses at finite Re can be neglected.Credit line: This article has been submitted to the Physics of Fluids -a link to the final version will be provided once published.

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Massive cluster impact mass spectrometry: A new desorption method for the analysis of large biomolecules

Mahoney

Perel

Ruatta

et al. 1991

Rapid Comm Mass Spectrometry

132

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A new ion desorption method is described that utilizes a primary beam of massive, multiply charged cluster ions to generate secondary ions of peptides in a glycerol matrix. The massive cluster ion beam is generated via electrohydrodynamic emission using a 1.5 M solution of ammonium acetate in 30% aqueous glycerol. Negative ion spectra of peptides obtained using this technique show greatly decreased relative intensities for fragment ions and 'chemical noise' background when compared to spectra obtained using a xenon atom primary beam. The near absence of fragments derived from radiation damage to the sample solution is attributed to the impact of primary particles with energies less than 1 eV/nucleon.

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Operational Characteristics of Colloid Thrusters

Cited by 14 publications

References 4 publications

Additively manufactured MEMS multiplexed coaxial electrospray sources for high-throughput, uniform generation of core–shell microparticles

Additively manufactured MEMS multiplexed coaxial electrospray sources for high-throughput, uniform generation of core–shell microparticles

Electrified cone formation in perfectly conducting viscous liquids: Self-similar growth irrespective of Reynolds number

Massive cluster impact mass spectrometry: A new desorption method for the analysis of large biomolecules

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