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Generation of charged droplets by field ionization of liquid helium

Tsao, Chun-Cheng and Lobo, Julio D. and Okumura, Mitchio and Lo, Shui-Yin (1998) Generation of charged droplets by field ionization of liquid helium. Journal of Physics D: Applied Physics, 31 (17). pp. 2195-2204. ISSN 0022-3727. http://resolver.caltech.edu/CaltechAUTHORS:TSAjpd98

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Abstract

Positively charged helium droplets were produced by ionization of liquid helium in an electrostatic spraying experiment, in which fluid emerging from a thin glass capillary was ionized by applying a high voltage to a needle inside the capillary. At 2.2 K, fine droplets (<10 mu m in diameter) were produced in pulsed sprays or showers with total currents as high as 0.4 mu A at relatively low voltages (2-4 kV). Ionization was accompanied by a visible glow at the needle and glass tips. Droplet formation was suppressed at 3.5 K. In contrast, liquid nitrogen formed a well-defined Taylor cone with droplets having diameters comparable to the jet (approximate to 100 mu m) at much lower currents (3 nA) and higher voltages (9 kV), in agreement with previous results. The mechanism for charging in these liquids was proposed to be field ionization, identical to the processes leading to conduction in cryogenic insulating liquids observed by Gomer. The high currents resulting from field ionization in helium, together with the intrinsically low surface tension of helium I, led to charge densities that greatly exceeded the Rayleigh limit, thus preventing formation of a Taylor cone and resulting in Coulomb explosion of the liquid.


Item Type:Article
Additional Information:© Institute of Physics and IOP Publishing Limited 1998. Received 27 October 1997. Print publication: Issue 17 (7 September 1998). This work was supported by American Technologies Group, Inc. We would like to thank Gilbert Wong for his many technical contributions.
Subject Keywords:DIELECTRIC-BREAKDOWN, EXCITATION, CLUSTERS, GASES
Record Number:CaltechAUTHORS:TSAjpd98
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:TSAjpd98
Alternative URL:http://dx.doi.org/10.1088/0022-3727/31/17/019
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:678
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:14 Sep 2005
Last Modified:26 Dec 2012 08:41

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