Demixing in a metal halide lamp, results from modelling

Beks, M.L.; Hartgers, A.; Mullen, J.J.A.M. van der

doi:10.1088/0022-3727/39/20/017

Cited by 18 publications

(37 citation statements)

References 14 publications

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“…with p i the partial pressure of the species i, and R iα the stoichiometric coefficient [16]. We solve a conservation equation for the elemental pressure…”

Section: Energy Balancementioning

confidence: 99%

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Metal-halide lamps in micro-gravity: experiment and model

Nimalasuriya¹,

Beks²,

Flikweert³

et al. 2008

J. Phys. D: Appl. Phys.

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The results from optical emission spectroscopy experiments of metal-halide lamps under the micro-gravity conditions on board the international space station are compared with the results of a numerical LTE model constructed with the platform Plasimo. At micro-gravity there is no convection which allows for easier modelling and for a separate study of the diffusion-induced radial segregation effect, undisturbed by convection. The plasma parameters that were experimentally determined and compared with the model were the Dy atom and ion density, the Hg ion density and the temperature.The model and experiments applied to a reference lamp burning on a plasma mixture of DyI 3 and Hg were found to be in reasonable agreement with each other. The cross-section for electron-Hg collisions was studied, it was found that the Rockwood values give the correct results. Experimental results guided a sensitivity analysis of the model for the Langevin cross-sections. The ratio of the ion densities Hg + /Dy + was found to be extremely sensitive for the cross-section of the elastic interaction σ (Hg, Dy + ) between the Dy ion and the Hg atom. The sensitivity analysis suggests that equating σ (Hg, Dy + ) to a value that is 10% higher than the Langevin cross-section is the best choice. We also found deviations from LTE in the outer regions of the plasma for relative radial positions of r/R > 50%.

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“…with p i the partial pressure of the species i, and R iα the stoichiometric coefficient [16]. We solve a conservation equation for the elemental pressure…”

Section: Energy Balancementioning

confidence: 99%

“…and a pseudo convective velocity c α [16]. The diffusion coefficient D i is calculated from the binary diffusion coefficients D ij by…”

Section: Energy Balancementioning

confidence: 99%

Metal-halide lamps in micro-gravity: experiment and model

Nimalasuriya¹,

Beks²,

Flikweert³

et al. 2008

J. Phys. D: Appl. Phys.

Self Cite

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show abstract

“…The ilas pictures also show a decrease in Dy density near the bottom of the lamp at 10g, which is caused by the decrease in cold spot temperature as explained in section Emission Spectroscopy. For a comparison between the experimental ilas results and numerical results obtained by modelling the reader is referred to literature Beks et al 2006Beks et al , 2008.…”

Section: Imaging Laser Absorption Spectroscopymentioning

confidence: 99%

The Metal-Halide Lamp Under Varying Gravity Conditions Measured by Emission and Laser Absorption Spectroscopy

Flikweert

Nimalasuriya

Kroesen

et al. 2009

Microgravity Sci. Technol.

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Diffusive and convective processes in the metal-halide lamp cause an unwanted axial colour segregation. Convection is induced by gravity. To understand the flow phenomena in the arc discharge lamp it has been investigated under normal laboratory conditions, micro-gravity (ISS and parabolic flights) and hyper-gravity (parabolic flights 2g, centrifuge 1g-10g). The measurement techniques are webcam imaging, and emission and laser absorption spectroscopy. This paper aims to give an overview of the effect of different artificial gravity conditions on the lamp and compares the results from the three measurement techniques.

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“…In plasmas in local thermodynamic equilibrium (LTE), where both the internal and reactive processes are at equilibrium, the diffusion model is used to account for the effects of elemental demixing or to calculate the reactive contribution to the thermal conductivity [1][2][3]. In combustion simulations and simulations of plasmas that are not in local thermodynamic equilibrium (NLTE), the diffusive flux is needed in the species continuity equations.…”

Section: Introductionmentioning

confidence: 99%