Metal halide lamps in the international space station ISS

Nimalasuriya, T Tanya; Flikweert, AJ Arjan; Haverlag, M Marco; Kemps, Pcm Pim; Kroesen, Gmw Gerrit; Stoffels, WW Winfred; Mullen, van der Jjam Joost

doi:10.1088/0022-3727/39/14/018

Cited by 21 publications

(51 citation statements)

References 14 publications

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“…In case of the 579 nm line of Hg, the intensity is calibrated and then the absolute radial intensity profile is used to numerically determine the temperature profile. In case the atomic or ionic lines of Dy are measured, the temperature profile is combined with the calibrated radial intensity profile of the additive into an absolute radial system density profile using equation (2) [9].…”

Section: The Experimentsmentioning

confidence: 99%

“…All measurements were done for different powers ranging from 70 to 150 W. The Hg ion distribution was also derived from the atomic Hg line using the Saha relation [12]. The results were reported in [9]. In order to cross-compare results of the various experiments done on metal-halide lamps and to compare the results from models to the experiments a reference lamp has been defined within the framework of the European project COST-529 [13].…”

Section: Introductionmentioning

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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Section: The Experimentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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

Nimalasuriya¹,

Beks²,

Flikweert³

et al. 2008

J. Phys. D: Appl. Phys.

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“…Obviously, these variations have a strong impact on the lamp emission and its efficiency. More details on the various measurements both under normal and microgravity conditions can be found in the references [8,9].…”

Section: Microgravity Experimentsmentioning

confidence: 99%

“…Due to dominant radial segregation there is less emission from the central lamp region under micro-gravity conditions.The microgravity measurements are performed in the international space station where the lamp shows no axial segregation as seen in the picture.The normal gravity data are taken with the same lamp just before launching.The data are reconstructed from spectrally resolved side-on measurements, which is reliable until the shaded area. [8] number 6 volume 37 37 -W.…”

Section: Microgravity Experimentsmentioning

confidence: 99%

Gravity's pull on arc lamp efficiency

Stoffels

2006

Europhysics News

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Wherever humans are present artificial light is used. It allows us to live and work indoors and outdoors at any time of the day. In densely populated areas, this literally lights up our planet as is clearly seen from outer space in figure 1. The 30 billion lamps operating worldwide are certainly a great commodity, but they come at a price. Not only do they cause serious light pollution, disturbing animal and plant life, they also have a huge energy need. Of the annual world electricity production, which is more than 1013 kWh, about 15-20 % is used for lighting applications [l]. A medium-to large-sized electricity plant has a production capacity of about one GW. An easy calculation shows that a few hundred electricity plants are operating continuously solely to supply the power for our lamps. Apart from depleting fuel reserves, this also results in an annual CO2 emission of about a billion ton and the attendant effects on ecology and climate. Obviously, lighting has a large social, economical as well as ecological impact.The best known lamp type is the incandescent lamp, where an electrical current heats a wire until it lights up. More than 100 years after Edison's invention, modern incandescent lamps are still not very efficient. Incandescent lamps produce only about 3% of all light whereas they consume 20% of the power needed for lighting. Discharge lamps are about 5 to 10 times more efficient. They can be grouped into two large families based on operating pressure. Tubular fluorescent lamps, commonly used in offices, are the bestknown example of low pressure lamps. High pressure lamps are commonly used if much light is needed, such as outdoor lighting. About 97% of all artificial light on Earth is produced using plasma technology [l, 21. Evidently, plasma lamps are essential in lighting, and any increase in their efficiency, even by as little as l%, has a large impact on preserving our natural resources and environment.The metal halide lamp is a high-pressure gas discharge lamp with a very high efficiency. Despite the fact that the lamp is widely used in outdoor lighting there are still several technological and scientific problems limiting its applicability. Some of the problems are related to a poor understanding of the physics of the gas discharge. Color separation, discussed here is one of them. But before describing the problem and discussing some experiments one should first review the basics of a metal halide lamp.A Fig. 2: A schematic view of a metal halide lam*p.The arc is produced between two tungsten electrodes in a mercury buffer gas of about 10 bar.The arc is confined inside an SiO, or AI, O, burner. Furthermore, a metal halide salt like Nal, Dyl ,, Sc13, orTll is added.After evaporation and dissociation, the excited metal atom is the main radiation source. Metal Halide LampsA metal halide lamp is derived from the better known mercury high-pressure arc discharge [2]. A schematic picture is shown in Fig. 2. An electric arc is maintained between two electrodes, which are sealed into the confming spa...

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“…Single-walled carbon nanotubes were produced by arc discharge method in hypergravity [11] and also microgravity [12,13]. The flow phenomena in metal-halide arc discharge lamps were intensively investigated under varying gravity conditions [14][15][16]. Low pressure radio frequency plasmas with dust particles are currently researched in various gravity conditions, too [17][18][19].…”

Section: Introductionmentioning

confidence: 99%

Hypergravity effects on glide arc plasma

et al. 2013

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Abstract. The behaviour of a special type of electric discharge -the gliding arc plasma -has been investigated in hypergravity (1g-18g) using the Large Diameter Centrifuge (LDC) at ESA/ESTEC. The discharge voltage and current together with the videosignal from a fast camera have been recorded during the experiment. The gliding of the arc is governed by hot gas buoyancy and by consequence, gravity. Increasing the centrifugal acceleration makes the glide arc movement substantially faster. Whereas at 1g the discharge was stationary, at 6g it glided with 7 Hz frequency and at 18g the gliding frequency was 11 Hz. We describe a simple model for the glide arc movement assuming low gas flow velocities, which is compared to our experimental results.

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Metal halide lamps in the international space station ISS

Cited by 21 publications

References 14 publications

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

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

Gravity's pull on arc lamp efficiency

Hypergravity effects on glide arc plasma

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