NDLI: Breakdown characteristics of metal halide plasma lamps

Content Provider	IEEE Xplore Digital Library
Author	Peters, S. Kettlitz, M. Wendt, M. Moss, A.
Copyright Year	2008
Description	Author affiliation: INP Greifswald, Greifswald (Peters, S.; Kettlitz, M.; Wendt, M.)
Abstract	Nowadays, metal halide plasma lamps are compact and efficient light sources. The dynamics of their breakdown stage are of actual research interest for improving reliable lamp ignition at comparatively low voltages. In order to study the influence of additives on the lamps' breakdown phase at high pressure, a simplified lamp geometry was used, containing 5 bar Xenon and some milligrams of different additives, like mercury. To avoid streamer wall interactions along the electrode axis (electrode gap ~5 mm), the model lamps exhibit a low aspect ratio. The discharges were operated by positive voltage ramps dU/dt of approximately 0.4-100 GV/s. The breakdown voltage and current were measured by fast probe techniques. Simultaneously the spatiotemporal evolution of a single streamer event was observed by a framing camera, providing sequences of four timeframes with a minimal exposure time of 10 ns. All investigated lamps were characterized by streamer propagation. At room temperature, lamps filled with 5 bar Xenon only showed one streamer, propagating directly between the two electrode tips. UV-lighting of the whole lamp body by a mercury low pressure discharge did not influence the breakdown voltage or the streamer evolution. An addition of 1 mg mercury changed this behavior. In this case the streamers branched more and the attachment on the electrodes was at different positions on and behind the electrode tips. Lighting the lamp by UV-radiation decreased the breakdown voltage very efficiently by about 4-8 kV, depending on the different lamp fillings. To enhance the mercury vapor pressure, the lamps were heated up in an oven, while the bulb temperature was measured by a thermo camera. At heating temperatures of 300 degC, mercury vaporized completely and the breakdown voltage was reduced by about 3 kV. But this effect is much less efficient than the voltage decrease of about 5-6 kV caused by UV-lighting for all bulb temperatures even for room temperature. Further experiments are planed to study the influence of other additives like NaI or iodine, which are constituents of commercial high intensity discharge lamps and can influence the ignition phase.
Starting Page	1
Ending Page	1
File Size	31549
Page Count	1
File Format	PDF
ISBN	9781424419296
ISSN	07309244
DOI	10.1109/PLASMA.2008.4591181
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2008-06-15
Publisher Place	Germany
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	High intensity discharge lamps Temperature measurement Electrodes Electric breakdown Additives Heating Ignition
Content Type	Text
Resource Type	Article
Subject	Atomic and Molecular Physics, and Optics Condensed Matter Physics Electrical and Electronic Engineering

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