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Title: Spectroscopic investigation of liquid helium excited by a corona discharge: evidence for bubbles and “red satellites”
Authors: Li, Z.-L.
Bonifaci, N.
Aitken, F.
Denat, A.
von Haeften, Klaus
Atrazhev, V. M.
Shakhatov, V. A.
First Published: 7-May-2009
Publisher: EDP Sciences
Citation: European Physical Journal, Applied Physics, 2009, 47 (2), 2821.
Abstract: The establishment of corona discharges close to a point electrode under both negative and positive high voltage in normal liquid helium (LHe) at 4.2 K is reported. The experiments were carried out at constant temperature and pressures ranging from 0.1–10 MPa. Visible luminescence emitted from the zone close to the tip revealed lines due to excited He atoms and molecules. The molecular luminescence showed hot band emissions with vibrational levels populated up to v=2. Rotational temperatures of 800 K were estimated showing that the excitations do not thermalise. With increasing pressure the lines shifted to shorter wavelengths and became broader. The magnitude of the increase in width deviated from what is expected from the gas phase and from classical line broadening theory and rather showed similarities to the behavior of bubbles in LHe. The detailed analysis of the rotational line intensity distribution revealed the presence of an additional radiator at the long wavelength side of molecular bands that we tentatively assign to “red satellite” emission. For corona discharges with positive tip polarities both atomic and molecular lines showed “red satellite" bands with much larger intensity than for negative polarity. The origin of the red satellite and the polarity dependence is unclear yet.
DOI Link: 10.1051/epjap/2009092
ISSN: 1286-0042
Type: Article
Rights: This paper was published as European Journal of Physics, Applied Physics, 2009, 47 (2), 2821. Copyright © 2009 EDP Sciences. The original publication is available at Doi: 10.1051/epjap/2009092
Appears in Collections:Published Articles, Dept. of Physics and Astronomy

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