Phase-resolved response of a metal-halide lamp

A.J. Flikweert, M.L. Beks, T. Nimalasuriya, G.M.W. Kroesen, J.J.A.M. Mullen, van der, W.W. Stoffels

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1 Citation (Scopus)


The metal-halide (MH) lamp sometimes shows unwanted colour segregation, caused by a combination of convection and diffusion. In the past we investigated the lamp, running on a switched dc ballast of 120 Hz, using a dc approximation for the distribution of the radiating species. Here we present phase-resolved intensity measurements to verify this approximation. The MH lamp contains Hg as buffer gas and DyI3 as salt additive; we measure the light emitted by Dy and by Hg atoms. An intensity fluctuation of ~25% close to the electrodes is found only. The observed fluctuations are explained by the cataphoresis effect and temperature fluctuations; the time scales are in the same order. Furthermore, measurements at higher gravity in a centrifuge (up to 10g) show that the effect becomes smaller at increasing gravity levels. From these results it is concluded that a dc approximation, which is generally assumed by lamp developers, is allowed for this MH lamp.
Original languageEnglish
Pages (from-to)035019-1/8
Number of pages8
JournalPlasma Sources Science and Technology
Issue number3
Publication statusPublished - 2009


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