One-mlb Colloid Thruster System Development

Zafran, S.; Beynon, J. C.; Kidd, P.; Shelton, H.; Jackson, F.

doi:10.2514/3.61920

Cited by 8 publications

(2 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…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

View full text Add to dashboard Cite

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.

show abstract

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

View full text Add to dashboard Cite

show abstract

“…They are often (necessarily in the case of FEEP) operated at only positive polarity alongside a neutralizing electron source [11][12][13][14][15]. As a particularly relevant example, the NASA-JPL Drag Reduction System (DRS) recently flown aboard the ESA led LISA Pathfinder mission demonstrated colloidal electrospray thrusters.…”

Section: Ilis Charge Neutralizationmentioning

confidence: 99%

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

Courtney¹,

Shea²,

Dannenmayer³

et al. 2018

Journal of Spacecraft and Rockets

View full text Add to dashboard Cite

Electrospray (ES) thrusters are unique in their ability to emit both positive and negative beams, each contributing similarly to thrust. Spacecraft charging could be prevented without a dedicated neutralizer if currents of simultaneously emitted opposing polarity beams were matched; despite a lack of implicit coupling between them. We discuss and evaluate experimentally both an active current-balance control circuit and a passive self-balancing configuration. Our highly ionic ES source includes a pair of machined porous glass ES emitter arrays in a single holder. In the passive configuration, unbalanced charge collection on a common floating extractor yields rapid charging towards artificially imposed 200 V limits without means for charge suppression, showing the unsuitability of that architecture. Active balancing of emitted currents was fully effective at charge neutralization during stable periods of emission, yet insufficient during potential alternations. We present methods to improve this approach, including demonstrating beam current modulation at up to 450 Hz. Direct thrust measurements when simultaneously emitting opposing polarity beams of the ionic liquid 1-ethyl-3-methylimidazolium tetrauoroborate are presented. Direct thrust measurements up to 35 µN were in excellent agreement with commanded levels and computations based on measured currents (up to 190 µA) and voltages (up to 2100 V).

show abstract

Polymer-based electrospray device with multiple nozzles to minimize end effect phenomenon

Tran

Byun

Nguyen

et al. 2010

Journal of Electrostatics

View full text Add to dashboard Cite

One-mlb Colloid Thruster System Development

Cited by 8 publications

References 3 publications

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

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

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

Polymer-based electrospray device with multiple nozzles to minimize end effect phenomenon

Contact Info

Product

Resources

About