Hostname: page-component-745bb68f8f-f46jp Total loading time: 0 Render date: 2025-01-09T21:57:02.929Z Has data issue: false hasContentIssue false
  • English
  • Français

The structure of electrospray beams in vacuum

Published online by Cambridge University Press:  14 May 2008

MANUEL GAMERO-CASTAÑO
MANUEL GAMERO-CASTAÑO*
Affiliation:
Department of Mechanical and Aerospace Engineering, University of California, Irvine, CA 92717, USA
Get access Rights & Permissions [Opens in a new window]

Abstract

Electrospray atomization of liquids in the cone-jet mode generates narrow droplet distributions with average diameters as small as a few nanometres. This ability is important for technologies such as colloid thrusters, nanoparticle generation and ion beam processes, and the optimization of these applications requires an understanding of the physics and structure of the associated beams. This paper presents a detailed experimental characterization of electrosprays in vacuum and formulates an analytical model of the beam. A key feature of our model is the use of a simplified expression for the electric field induced by the space charge. This simplification leads to a time-independent Eulerian formulation compatible with an analytical solution, in contrast to the direct simulation of a multitude of droplets which must be simultaneously tracked to account for Coulombic interactions. We find that the beams open up in an initial region relatively insensitive to the external electrodes, a process dominated by the electric repulsion between droplets and the initial droplet inertia. Although the external electric field modifies the trajectories of the droplets downstream of this initial region, the effect is moderate in our typical electrospray source and the analytical solution in the space charge region explains well the far-field beam structure observed experimentally. We also describe a numerical scheme that implements the full effect of the external electric field and provides a more accurate solution.

Type
Papers
Information
Journal of Fluid Mechanics , Volume 604 , 10 June 2008 , pp. 339 - 368
Copyright
Copyright © Cambridge University Press 2008

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

REFERENCES

Ashgriz, N. & Mashayek, F. 1995 Temporal analysis of capillary jet breakup. J. Fluid Mech. 291, 163–190.Google Scholar
Chandrasekhar, S. 1981 Hydrodynamic and Hydromagnetic Stability, pp. 515–576. Dover.Google Scholar
Cloupeau, M. & Prunet-Foch, B. 1989 Electrostatic spraying of liquids in cone-jet mode. J. Electrostat 22, 135–59.CrossRefGoogle Scholar
Collins, R. T., Harris, M. T. & Basaran, O. A. 2007 Breakup of electrified jets. J. Fluid Mech. 588, 75–129.Google Scholar
Enloe, C. L. & Shell, J. R. 1992 Optimizing the energy resolution of planar retarding potential analyzers. Rev. Sci. Instrum. 63, 1788–1791.CrossRefGoogle Scholar
Fenn, J. B., Mann, M., Meng, C. K., Wong, S. K. & Whitehouse, C. M. 1989 Electrospray ionization for mass spectrometry of large biomolecules. Science 246, 64–71.Google Scholar
Fernández de la Mora, J. 1992 The effect of charge emission from electrified liquid cones. J. Fluid Mech. 243, 561–574.Google Scholar
Fernández de la Mora, J. 2007 The fluid dynamics of Taylor cones. Annu. Rev. Fluid Mech. 39, 217–243.Google Scholar
Fernández de la Mora, J. & Loscertales, I. G. 1994 The current transmitted through an electrified conical meniscus. J. Fluid Mech. 260, 155–184.Google Scholar
Gamero-Castaño, M. & Hruby, V. 2002 Electric measurements of charged sprays emitted by cone-jets. J. Fluid Mech. 459, 245–276.Google Scholar
Gamero-Castaño, M. 2002 Electric-field-induced ion evaporation from dielectric liquid. Phys. Rev. Lett. 89, 147602.CrossRefGoogle ScholarPubMed
Gamero-Castaño, M. 2007 Induction charge detector with multiple sensing stages. Rev. Sci. Instrum. 78, 043301.Google Scholar
Gañán-Calvo, A. M. 1997 Cone-jet analytical extension of Taylor's electrostatic solution and the asymptotic universal scaling laws in electrospraying. Phys. Rev. Lett. 79, 217.Google Scholar
Gañán-Calvo, A. M. 1998 Generation of steady liquid microthreads and micron-sized monodisperse sprays in gas streams. Phys. Rev. Lett. 80, 285–288.CrossRefGoogle Scholar
López-Herrera, J. M. & Gañán-Calvo, A. M. 2004 A note on charged capillary jet breakup of conducting liquids: experimental validation of a viscous one-dimensional model. J. Fluid Mech. 501, 303–326.Google Scholar
Martínez-Sánchez, M. 2004 16.522 Space Propulsion. Massachusetts Institute of Technology OpenCourseWare. http://ocw.mit.edu/OcwWeb/Aeronautics-and-Astronautics/16-522Spring2004/CourseHome/index.htm.Google Scholar
McEwen, A. B., Ngo, H. L., LeCompte, K. & Goldman, J. L. 1999 Electrochemical properties of imidazolium salt electrolytes for electrochemical capacitor applications. J. Electrochem. Soc. 146, 1687–1695.Google Scholar
Morse, P. M. & Feshbach, H. 1953 Methods of Theoretical Physics, Part II, p. 1284. McGraw-Hill.Google Scholar
Reiser, M. 1994 Theory and Design of Charged Particle Beams p. 191. John Wiley.Google Scholar
Riddick, J. A, Bunger, W. B. & Sakano, T. K. 1986 Organic Solvents. Physical Properties and Methods of Purification, 4th edn. Wiley.Google Scholar
Shelton, H., Hendricks, C. D. & Wuerker, R. F. 1960 Electrostatic acceleration of microparticles to hypervelocities. J. Appl. Phys. 31, 1243–1246.Google Scholar
Taylor, G. I. 1964 Disintegration of water drops in an electric field. Proc. R. Soc. Lond. A 280, 383–397.Google Scholar