Axial segregation in high intensity discharge lamps measured by laser absorption spectroscopy
- Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven (Netherlands)
High intensity discharge lamps have a high efficiency. These lamps contain rare-earth additives (in our case dysprosium iodide) which radiate very efficiently. A problem is color separation in the lamp because of axial segregation of the rare-earth additives, caused by diffusion and convection. Here two-dimensional atomic dysprosium density profiles are measured by means of laser absorption spectroscopy; the order of magnitude of the density is 10{sup 22} m{sup -3}. The radially resolved atomic density measurements show a hollow density profile. In the outer parts of the lamp molecules dominate, while the center is depleted of dysprosium atoms due to ionization. From the axial profiles the segregation parameter is determined. It is shown that the lamp operates on the right-hand side of the Fischer curve [J. Appl. Phys. 47, 2954 (1976)], i.e., a larger convection leads to less segregation.
- OSTI ID:
- 20714118
- Journal Information:
- Journal of Applied Physics, Vol. 98, Issue 7; Other Information: DOI: 10.1063/1.2073970; (c) 2005 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
- Country of Publication:
- United States
- Language:
- English
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