Why does the lumen maintenance of sodiumscandium metal halide lamps improve by VHF operation?
| Autor: | W Hitchcock, W. Van Erk, G M J F Luijks |
|---|---|
| Přispěvatelé: | Retired employee Philips Lighting, Advanced Development Lighting, Philips Lighting, Philips Lighting Company |
| Jazyk: | angličtina |
| Rok vydání: | 2011 |
| Předmět: |
Acoustics and Ultrasonics
chemistry.chemical_element Halide 02 engineering and technology Low frequency 01 natural sciences law.invention law 0103 physical sciences Autotransformer Scandium Common emitter 010302 applied physics Chemistry business.industry 021001 nanoscience & nanotechnology Condensed Matter Physics Cathode Surfaces Coatings and Films Electronic Optical and Magnetic Materials Lumen maintenance Electrode Physical Sciences Optoelectronics 0210 nano-technology business |
| Zdroj: | Journal of Physics D: Applied Physics Journal of Physics D: Applied Physics, IOP Publishing, 2011, 44 (22), pp.224001. ⟨10.1088/0022-3727/44/22/224001⟩ |
| ISSN: | 0022-3727 1361-6463 |
| DOI: | 10.1088/0022-3727/44/22/224001⟩ |
| Popis: | Lifetime experiments show that sodium–scandium metal halide lamps perform better on very high frequency (VHF) drivers than on low frequency (LF) constant wattage autotransformer (CWA) ballasts. The question why, will be addressed with focus on arc tube aspects. It is argued that at high frequency operation sodium loss is less, and that the absence of thermal fluctuations in the electrode tip causes less damage and cracking to this part of the electrode. Sudden lm W−1 drops, observed with CWA-operated lamps, most probably occur when the arc attaches on such a corroded and cracked surface. Thorium is effective as an emitter both in the CWA and the VHF operation mode, despite the absence of cataphoretic transport to the cathode in the VHF case. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
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