High-pressure Discharge Lamps Research Articles

Realization of an dimmable electronic ballast for a discharge lamps fed by an LSCSCP circuit and a PFC stage

<p>This paper presents an electronic ballast for discharge lamps. The ballast consists of two stages: i) a boost-buck chopper that performs the power factor correction and provides an approximately variable DC link voltage to drive the second stage and ii) a half-bridge MOSFET inverter with an improved series-parallel inductor-capacitor-inductor (LsCpLp) resonant circuit to drive the high-frequency discharge lamp. The electronic ballast designed here is a multi-purpose ballast which was experimentally tested for high-pressure sodium discharge lamps 150 W and metal halide lamps 150 W. It was revealed that this mode of operation makes it possible to vary and dim the light of the lamp and to improve the quality of the power supply while reducing the harmonic currents in networks.</p>

Simulation And Development Of Electronic Ballast for High Pressure Discharge Lamps

The advantages and disadvantages of using electromagnetic ballasts for power supply of high pressuredischarge lamps (HPDL) are considered. The advantages of using electronic ballasts for supplying HPDL are shown. The analysis is fulfilled of the operation of the HPDL when powered by a high-frequency current, in particular, high-pressure sodium lamps (HPSL). It is indicated that when high-pressure discharge lamps are supplied with a high-frequency current, acoustic resonance may appear. The basic requirements to be met by electronic ballasts for HPSL have been determined. The topology of construction of electronic ballasts for supplying HPDL with a capacity of up to 1 kW has been selected. It has been established that half-bridge converters with inductive ballast and active power factor corrector (PFC) allow maintaining a stable power on the lamp while changing its parameters and efficiency. Mathematical modelling of the electronic ballast based on a half-bridge converter and an ignition device for the sodium discharge lamps DNaT type has been carried out. According to the proposed topology, the electronic ballast was developed for a DNaT 600 lamp powered from the 380 V network. Test operation of the lamps confirmed the reliability of the proposed electronic ballast topology.

Preventing method of acoustic resonance in the high-pressure discharge lamps

Abstract The article analyzes available methods for preventing acoustic resonance of high pressure lamps. A new method is proposed, the main idea of which is the filing of a high-voltage lamp modulated by a pseudo-random signal. An analysis of the spectral characteristics of the signal entering the lamp is made, the mathematical modeling of the set of a “discharge lamp - prototype of the device” - is implemented, which implements the proposed control method of the lamp. The results of simulation and oscillograms, taken from the prototype, which confirms the results of theoretical research, are presented.

Behaviour of street-lighting feeders supplying traditional and new light-emitting diode lamps

This study aims at the investigation of street-lighting feeders and the technical issues which are caused by the substitution of the traditional lamps with the light-emitting diode (LED) ones. Three types of lamps are investigated: fluorescent, high-pressure discharge and LED lamps. Load static behaviour and the total harmonic distortion are examined experimentally, while lighting feeder behaviour is investigated numerically. Experimental results show that the total harmonic distortion and power factor of LED lamps are significantly higher than that of traditional lamps. Numerical investigations have shown that the total lighting feeder behaviour is independent from the lamp types.

A broadband LED source in visible to short-wave-infrared wavelengths for spectral tumor diagnostics

Various tumor types exhibit the spectral fingerprints in the absorption and reflection spectra in visible and especially in near- to short-wave-infrared wavelength ranges. For the purpose of spectral tumor diagnostics by means of diffuse reflectance spectroscopy, we developed a broadband light emitting diode (LED) source consisting of a blue LED for optical excitation, Lu3Al5O12:Ce3+,Cr3+ luminescent garnet for visible to near infrared emissions, and Bismuth doped GeO2 luminescent glass for near-infrared to short-wave infrared emissions. It emits broad-band light emissions continuously in 470–1600 nm with a spectral gap at 900–1000 nm. In comparison to the currently available broadband light sources like halogen lamps, high-pressure discharge lamps and super continuum lasers, the light sources of this paper has significant advantages for spectral tissue diagnostics in high-spectral stability, improved light coupling to optical fibers, potential in low light source cost and enabling battery-drive.

Modeling of diffusive plasmas in local thermodynamic equilibrium with integral constraints: application to mercury-free high pressure discharge lamp mixtures

The mercury free lamp model previously discussed in Gnybida et al (2014 J. Phys. D: Appl. Phys. 47 125201) did not account for self-consistent diffusion and only included two molecular transitions. In this paper we apply, for the first time, a self-consistent diffusion algorithm that features (1) species/mass conservation up to machine accuracy and (2) an arbitrary mix of integral (total mass) and local (cold spot) constraints on the composition. Another advantage of this model is that the total pressure of the gas is calculated self consistently. Therefore, the usage of a predetermined pressure is no longer required.Additionally, the number of association processes has been increased from 2 to 6. The population as a function of interatomic separation determines the spectrum of the emitted continuum radiation. Previously, this population was calculated using the limit of low densities. In this work an expression is used that removes this limitation. The result of these improvements is that the agreement between the simulated and measured spectra has improved considerably.

Transient Hg, Ba+, Ca+ and Y+ Optical Emission Lines of a Mercury HID Lamp Exposed to X-Ray: Thermal Analysis of the Tungsten Electrode with Emissive Mixture Based on Barium, Calcium and Yttrium

A study is made on optical emission spectrum modification during X-ray exposure, in the case of a high-pressure mercury discharge lamp operated at several powers. A strong dependence on the lamp operating power for all the spectral lines intensities is observed. Erosion of the emissive mixture based on barium, calcium and yttrium compounds is evidenced by higher values recorded for spectral line intensities in all cases of X-ray exposure compared with those corresponding to non-irradiated lamps. Boltzmann type functions fitted the experimental data of measured optical emission intensities versus time for Ba+, Ca+ and Y+ lines. However, X-ray influence on plasma electron temperature is not significant. The spectroscopic data are correlated with the results of electrical measurements and of thermal analysis performed for the electrode having the emissive mixture based on barium, calcium and yttrium compounds. A qualitative explanation of the results is also given.

Microstructural Characterisation of Glass Ceramics as a Component Part of High Pressure Discharge Lamps

Abstract The investigation presented is of part of a high pressure discharge lamp. The heart of the lamp is a ceramic burner which is sealed with a so-called glass solder, a glass ceramic comprised of a mixture of Oxides (Dysprosium Oxide, Aluminium Oxide and Silicon Oxide). Two different chemical compositions of glass solder, which are part of type of a composite material comprised of a broad spectrum of materials, are compared microscopically. The morphology of solidification, which has an effect on the operating life of the lamps is characterised using various classical methods such as optical light microscopy and Scanning Electron Microscopy.

A study of the convective flow as a function of external parameters in a high-pressure metal halide discharge lamp (HgDyI3)

This paper deals with the modelling of the convection processes in metal–halide lamp discharges (HgDyI3). For this, we realized a 3D model, a steady, direct current powered and time-depending model for the solution of conservation equations relative to mass, momentum, and energy. After validation, this model was applied to the study of the effect of some parameters that have appeared on major transport phenomena of mass and energy in studying the lamp. Indeed, the electric current, the atomic ratio (Hg/Dy), and the effect of the convective transport have been studied.

Nghiên cứu chọn giống lúa thơm không ảnh hưởng quang kỳ, năng suất cao, phẩm chất tốt

A aromatic traditional rice variety “Nang Thom” mainly planted in Ben Luc district, Long An province. Flowering stage was affected by photoperiod due to high pressure discharge lamps along the Ho Chi Minh city – Trung Luong highway. Solving this problem, a set of 10 new aromatic rice varieties were tested. This experiment was carried out in three crop seasons during 2012 to 2014 based on the Tests for Value of Cultivation and Use of Rice Varieties (10 TCN 558-2002). Results showed that two elite breeding lines TLA1 and TLA4 performed well, the yield ranged from 5.80 to 6.50 ton/ha, amylose content less than 20%, protein content >7% and the lines showed fairly good tolerance to insects and diseases.

Development of a technique for identification of model parameters of high-pressure discharge lamp

The technique for identification (determination of the parameters) of the model of high-pressure discharge lamp by comparing the simulated and experimental data was developed. Searching for the model parameters is divided into two main stages: 1) determining the degree of influence of each parameter change on the model output; 2) directly searching for the minimum functional divergence. Divergence evaluation is carried out by determining the value of the functional - the sum of the squares of divergences during the studied time period. When searching for minimum divergence, a corresponding set of model parameters is determined. The technique for determining the parameters of the mathematical model of high-pressure discharge lamp was designed to determine such parameters of the model, which allow to describe it with the necessary precision. Trial computational experiment showed the performance of the model parameter determination program, developed using the technique. It was found that the models that are based on the current-voltage characteristics of lamps are promising. The need to determine the model parameters is caused by the requirement for the accuracy of the research, and the availability of regular deviations in characteris­tics of lamps of the same type from different manufacturers, batches and even between units in batches from that of manufacturers and general. Ensuring the model accuracy is also important in developing and creating complex control systems that can be realized with microprocessor control, where the model is used for calculating the control object behavior and selecting control signals.

Numerical investigation on the replacement of mercury by indium iodide in high-intensity discharge lamps

Mercury-free high-pressure discharge lamps have been studied by means of a radial-dependent model. Xenon and indium iodide are chosen as start gas and buffer, respectively. Local thermodynamic equilibrium is assumed with a single temperature for all species. The model consists of the coupled description of the balance equation for the plasma temperature with the radiation transport equation. The plasma composition is calculated according to the Guldberg–Waage, Boltzmann and Saha laws. These laws were supplemented by additional equations specifying the total pressure, constant element ratios and quasineutrality. The model takes into account atomic, molecular as well as continuum radiation. The broadening of the optically thick lines is approximated by Stormberg's approach. The predicted spectrum is compared with a measured one and shows good agreement on a qualitative scale. From this comparison it is concluded that the largest part of the continuum radiation is produced by the free–free and free–bound AX transition in InI.

Iterative Boltzmann plot method for temperature and pressure determination in a xenon high pressure discharge lamp

The Boltzmann plot method allows to calculate plasma temperatures and pressures if absolutely calibrated emission coefficients of spectral lines are available. However, xenon arcs are not very well suited to be analyzed this way, as there are only a limited number of lines with atomic data available. These lines have high excitation energies in a small interval between 9.8 and 11.5 eV. Uncertainties in the experimental method and in the atomic data further limit the accuracy of the evaluation procedure. This may result in implausible values of temperature and pressure with inadmissible uncertainty. To omit these shortcomings, an iterative scheme is proposed that is making use of additional information about the xenon fill pressure. This method is proved to be robust against noisy data and significantly reduces the uncertainties. Intentionally distorted synthetic data are used to illustrate the performance of the method, and measurements performed on a laboratory xenon high pressure discharge lamp are analyzed resulting in reasonable temperatures and pressures with significantly reduced uncertainties.

Light emitting diodes: Light engines to simplify and economize advanced microscopy

THE old adage, ‘‘A picture is worth a thousand words,’’ is especially true in biological research, with microscopic images serving to mark the development of key concepts in biology since Hooke first described ‘‘cells’’ in thin slices of cork (1). More than 400 years later, microscopic imaging still serves as a primary data source for biological research, with increasingly advanced techniques that provide information on molecular scale interactions and dynamics. Such advanced molecular imaging techniques take advantage of ever more sophisticated light sources, optics, detectors, and image processing methods, many of which can be quite complex and expensive. At the same time, new technologies and production methods, many driven by the consumer market, have resulted in key components of imaging systems becoming smaller, simpler, and cheaper. The convergence of these effects is having profound effects on our options for light sources for microscopic imaging. The properties of the illumination source are critical to many advanced optical microscopy methods. Lasers play a key role in many of these owing to the monochromatic and coherent nature of their light, plus their ability to be pulsed and otherwise controlled. However, illumination with high-pressure mercury gas discharge or xenon lamps is still the standard for most imaging applications. These light sources provide bright, broad-spectrum excitation (300–900 nm) that can be easily selected by excitation filters for fluorescent imaging applications. However, there are quite a few disadvantages that limit the wide-spread of mercury or xenon lamps-based microscopy system in biological applications. First, sometimes these traditional light sources are too bright and harmful for the living organisms being studied. Excessive brightness can cause rapid photo-bleaching of the dyes used to stain the cells/ tissues. UV light especially, if not blocked, can have significant deleterious effects on live cells. Second, there are substantial costs involved in using mercury or xenon lamps because of their relatively short lifespan. The life of a mercury lamp is usually several hundred hours, and the intensity of these lamps decays progressively during this time. In addition, gas discharge lamps require some time to warm up before lamp intensity reaches steady state. Therefore, once mercury lamps are turned on, they have to be left on for hours to enable fluorescent measurements as needed without delay, thereby further shortening the lamp lifetime. Third, there are also some hazards issues of using mercury or xenon lamps. These lamps generate a significant amount of heat and therefore introduce complications when used in a confined space. When mercury lamps die, they can explode and damage the lenses or mirrors within the lamp housing. These factors combine to make gas discharge lamps inconvenient for lab-based applications and impractical for field applications, including use in portable, miniature, or low cost imaging devices. By contrast, light-emitting diodes (LEDs) show great pro

Temperature measurements at thoriated tungsten electrodes in a model lamp and their interpretation by numerical simulation**The paper is dedicated to the memory of the late Dr G M J F Luijks in appreciation of his outstanding pioneering work on high pressure discharge lamps, particularly his contribution to an understanding of the gas phase emitter effect in these lamps in cooperation

An atmospheric pressure argon arc is operated with dc currents of different amplitudes in a model lamp between electrodes made of pure and thoriated tungsten. Temperature measurements are performed at these electrodes with a CCD camera being calibrated at λ = 890 nm in absolute units of surface radiance and an interference filter for this wavelength. Temperature distributions are deduced from the CCD camera records of the electrodes assuming that they are grey body radiators. The records show a diffuse mode of attachment at the cathode. Doping the electrode with ThO2 causes a reduction in the cathode temperature by an amount of the order of 1000 K. On the other hand the anode temperature is weakly increased by a doping with ThO2. A reduction in the work function ϕ of the cathode from 4.55 to 3 eV is found by a comparison with cathode temperatures obtained by a numerical simulation of the diffuse mode of arc attachment with a well established cathode boundary layer model. Moreover, it is noted that the reduction is independent of the amount of ThO2 by which the electrode material is doped indicating that the work function of thoriated cathodes is the result of a self adjustment to the work function minimum at a thorium coverage of Θ ≈ 0.5. The weak influence of ThO2 on the anode temperature shows that the average work function of the anode does not depend on the thorium content of the electrode. The results are explained by a thorium ion current, by which evaporated thorium is repatriated to the cathode surface.

Ignition of High-Pressure Discharge Lamps Supported by Microdischarges

Auxiliary ignition wires are a well-known tool to support the ignition of high-pressure discharge lamps. The effect of these wires in cylindrical high-pressure discharge lamps made from polycrystalline alumina is visualized by applying high-voltage pulses of a spark tester to one of the electrodes. Microdischarges are observed, which are capable to support lamp ignition.

Experimental and Theoretical Wall Temperatures of Hg HID Lamps

Thermography is an established experimental method to measure wall temperatures of high-pressure discharge lamps resulting in 2-D images. However, theoretical models, including the heat balance of the tube wall, are usually based on a cylinder symmetric 2-D model, where the tube wall surface is represented by a 1-D line. In this paper, a comparison between experimental and theoretical results are presented, where a 2-D thermographic image is reconstructed from the model calculations. This allows visualizing and discussing of some capabilities and limitations of the theoretical model.

Radio frequency emission from high-pressure xenon arcs: A systematic experimental analysis of the underlying near-anode plasma instability

High-pressure Xe discharge lamps at DC operation can show unwanted strong RF (radio-frequency) emission to beyond 1 GHz, correlated to a sharp periodic lamp-voltage instability in the near-anode plasma with a pulse repetition rate ε of 1–10 MHz. The physical origin of the instability is unclear. Here, its existence and pulse rate have been measured as a function of arc current I = 0.2–1.2 A and anode temperature Ta = 1700–3400 K independently, in experimental lamps with pure-tungsten electrodes and a Xe operating pressure around p = 10 MPa. Surprisingly, the instability is not affected by I or current density j but exists if Ta is lower than a threshold value around 2800–2900 K. The pulse rate ε is simply a rising linear function of the inverse anode temperature 1/Ta, with only a small I-dependent correction. The average anode heat load is slightly lower in the unstable regime and possibly depends on ε. The results allow a consistent re-interpretation of earlier and present experimental observations and should be both a valuable help in practical lamp engineering and a tight constraint for future theories of this effect.

Mercury-free high pressure discharge lamps dominated by molecular radiation

High intensity discharge (HID) lamps dominated by molecular radiation offer a very promising alternative for use in future light sources. They are able to deliver competitive efficacies of about 110 lm W−1 and higher, excellent colour rendering index above 90 and a correlated colour temperature in the 3000–4000 K region at the operating point near the Planckian locus. Moreover, these lamps are opening up the possibility of dimming. Due to the fact that they are able to omit mercury they are environmentally friendly.The emission spectra generated by these HID lamps differ significantly from those of conventional lamps. The reason for this is the dominance of molecular radiation processes. In comparison with conventional HID lamps atomic contributions are usually rather small. In the present case they amount to less than about 10% of the total intensity in the visible range.

An Alternative Optical Method for Acoustic Resonance Detection in HID Lamps

Acoustic resonances are observed in high-pressure discharge lamps operated with ac input modulated power frequencies in the kilohertz range. This paper describes an optical resonance detection method for high-intensity discharge lamps using computer-controlled cameras and image processing software. Experimental results showing acoustic resonances in high-pressure sodium lamps are presented.