High Pressure Metal Halide Lamps Research Articles

X-ray absorption tomography of a high-pressure metal-halide lamp with a bent arc due to Lorentz-forces

Due to its practical importance x-ray absorption (XRA) tomography is becoming a widely applied technique for reconstruction of gas temperature distribution in high intensity discharge lamps. Most of the previous papers have dealt with the cylindrically symmetric plasmas that normally occur when lamps are burned vertically. In this work, a XRA tomographic diagnostic is applied for the first time to a high-pressure metal-halide lamp with a bent arc. X-ray lamp-off and lamp-on measurements have been made for two orthogonal directions. The maximum entropy-based algorithm was applied for the reconstruction of local absorption coefficients which are directly related to the local values of mercury density and plasma temperature. For correct reconstruction of the temperature profile at the edges a new numerical strategy based on the adaptive regularization parameter is developed. This strategy allows use of the measured value of the wall temperature as a reference point to obtain a quantitative temperature distribution.

Prediction of Spectra of High-Pressure Metal Halide Discharge Lamps Containing Rare-Earth Fillings

In the development of high-pressure metal halide lamps there is a growing need for lamps with good color rendering properties. To meet these requirements rare-earth halides are added more often. Due to the multi-line atomic spectra of rare-earth species it is possible to fill the visible spectrum almost completely, which is the basis of the good color rendering properties of lamps containing rare-earth species. In order to support the development of such lamps numerical plasma models are being developed. These models and their verification require that good fundamental data is available for the radiative properties of the rare earth species. In this article an interpolation method is presented that can yield an indication of oscillator strengths of lines that are not known, based on a fit to a Boltzmann plot (log intensity against lower level energy), using oscillator strengths of lines that are already known to create the Boltzmann plot.

UVABA therapy for psoriasis: Efficacy with shortened treatment times with the combined use of coal tar, anthralin, and metal halide ultraviolet machines

Rapid clearing of psoriasis in a psoriasis treatment center setting has been obtained with a combination of short-contact coal tar, phototherapy from high-pressure metal halide lamps (consisting of UVA and UVB), and short-contact high-potency anthralin therapy. These intensive 1 1/2- to 2-hour treatment sessions done three or four times weekly were as efficacious as reported responses to PUVA therapy or conventional psoriasis day care therapy. The treatment schedule allows minimal time away from work, decreased hours per week in contact with crude coal tar, shortened UV treatment times, decreased cost, and a low risk of side effects. It is suggested that the use of UVA and UVB combined with anthralin (UVABA) is effective for many patients with moderate to severe psoriasis.

Saturated laser-induced fluorescence in a high-pressure metal halide discharge

Local measurements of the saturated laser-induced fluorescence (LIF) signal from pulsed laser excitation of the 6 3 P1 resonance state of Hg have been obtained in a high-pressure metal halide lamp. Hg atoms were excited at 436 nm (6 3P1 →7 3S1 ) and the laser-induced fluorescence was detected at 546 nm (7 3S1 →63P2 ). The LIF signals were obtained as a function of radial position and the ac phase angle. The LIF signals were corrected for the optical depth of the fluorescence. The LIF measurements were made under saturated conditions to minimize the spatial dependence of the fluorescence quantum efficiency in the discharge. The 6 3P1 density was a maximum at the arc center and monotonically decreased towards the wall. The relative 6 3 P1 profile was broader at the current zero crossing than at the current maximum. The 6 3 P1 density was undermodulated during the ac phase at the arc center compared to predictions based on the Hg 577-nm emission, suggesting a departure from local thermodynamic equilibrium. At a reduced radius of 0.62, the 6 3 P1 density was almost independent of phase angle. Estimates of the 6 3 P2 density were obtained from the optical depth. LIF measurements were also obtained by exciting the 6 3P2 level of Hg at 546 nm and detecting the fluorescence at 436 nm. The spatial and phase angle dependence of the LIF signals from a mercury discharge were very similar to the results from a metal halide lamp.

Dr Honle Sol Sun simulation systems from Uvalight Technology Ltd

The Dr Honle range of Sol Sun simulation machines represent a new concept in UV technology. The novel high pressure metal halide lamp and filter combination reproduces the spectrum of natural sunlight almost exactly with an intensity up to 9 times greater.

The in vivo growth and development of micropropagated Elatior begonias (Begonia x hiemalis): I. Study on the effect of lighting and substrate

Micropropagation is an efficient way to produce pathogen-free Elatior begonias. However, certain problems arise when these plants are used in commercial pot plant production. The plants grow too luxuriantly, the root collars remain thin and flowering is delayed. To investigate the impact of the growing method, an experiment with different sources of supplementary light and different substrates was arranged in spring 1987. The following Elatior begonia cultivars were studied: ’Afrodite’, ’Afrodite Special’,'Afrodite Rosa’, ’Mandela’, ’Barbara’, ’Connie’, ’Marja’ and ’Sirene’. Four different lamp types were used: high pressure sodium lamps (Airam SNaKd 330 W), high-pressure mercury lamps (Airam HgLX 400W), high-pressure metal halide lamps (Philips HPI/T 375 W) and, as a control treatment, incandescent lamps of 100W. The plants were potted in B2-peat (Sphagnum peat with moderate fertilization and medium sieving grade), B2-peat (3 parts) plus perlite (1 part) or B2-peat (2 parts) plus perlite (2 parts). The plants lighted with SNaKd or HgLX lamps were the highest, the broadest and the first to reach anthesis and the sale stage. The plants in the control group were the smallest and the last to reach anthesis and the sale stage. The effect of the substrate on the time required to reach anthesis and the sale stage was clear only in the cultivar ’Afrodite Special’; when potted in peat-perlite 2 + 2, its plants flowered 2 weeks later than in other substrate mixtures. The height and the width of the plants were not greatly affected by the substrate. None of the lamp types or substrates clearly increased the number of flower buds or the diameter of the root collar. The proportion of saleable plants varied with the cultivar, lighting and substrate. In most cultivars it was below 50 %. The chief factors reducing saleability were luxuriant growth, weak flowering and oblique growth habit.

The effect of supplemental irradiation with different light sources on growth and flowering of gloxinia ( Sinningia speciosa (Lodd.) Hiern)

The relative efficiency of a warm white fluorescent lamp, a high-pressure metal halide lamp, a high-pressure sodium lamp and a low-pressure sodium lamp on growth and flowering of three cultivars of Sinningia speciosa (‘Burgdorf’, ‘Gerda Lodder’, ‘Peace’) has been studied under winter conditions at latitude 60°N. The light sources were compared at three irradiance levels (10, 14 and 18 W m −2 in the wavelength range 400–1000 nm). The growth rate and growth habit were markedly affected by both light source and irradiance level, and specific cultivar reactions were recorded. The differences recorded between light sources in rate of development, dry weight production, plant diameter and adventitious shoot formation were in general more pronounced at lower than at higher irradiance levels.

Operation of metal-halide lamps on square wave supply

In a comparison of the operation of high pressure metal halide lamps, on either sine or square wave supplies lamps have been found to operate satisfactorily using both choke and choke/capacitor ballasts. The dependence of lamp power on supply waveform and ballast type has been measured on 250 W MBI lamps for a supply voltage range of 210-270 V. Analysis of the lamp circuit for square wave supply voltage has been made using the simplifying assumption that the lamp voltage is independent of current. Expressions derived for the current waveforms and the power dissipated in the lamp are shown to agree well with experimental values. Although the analysis is used to predict the behaviour of metal-halide lamps, it is equally valid for other types of discharge lamps.

Lighting systems in major New Zealand controlled environment facilities

The lighting systems used in New Zealand in the Department of Scientific and Industrial Research (DSIR) Climate Laboratory controlled environment rooms, the Forest Research Institute (FRI) tree growth rooms, and the DSIR-designed reach-in controlled environment chambers are described. All lighting systems are based on high-pressure discharge lamps which can be used with varying amounts of incandescent light supplementation. The main lighting type used in the Climate Laboratory controlled environment rooms is the high-pressure metal halide lamp, that in the FRI rooms the high-pressure mercury-vapour fluorescent lamp with internal reflector, and that in the reach-in chambers a high-pressure mercury halide lamp. Details of lighting rig design, of irradiance levels obtainable, vertical and horizontal light distribution patterns and spectral quality are presented for each system. The photosynthetic irradiance levels available at 2–3 m below the lighting systems in all of these controlled environment systems are high (180–200 W m −2 PAR). In the Climate Laboratory and FRI growth rooms peak sunlight values of approximately 400 W m −2 PAR (approximately 10,000 ft.c.) have been achieved. A discussion of the performance of these systems is also presented.