Discharge Lamps Research Articles

Heat-assisted slurry sampling GFAAS method for determination of lead in food standard reference materials

A valid method based on heat-assisted slurry sampling graphic furnace atomic absorption spectrometry (HASS-GFAAS) was developed for the accurate determination of trace Pb in food standard reference materials (SRMs). The HASS technique significantly improved Pb recovery and precision compared to conventional slurry sampling techniques. The optimized HASS procedure was performed as follows: first, the sample (particle size≤150μm) was diluted with 0.05% (v/v) Triton X-100 containing 2% HNO3 and 1% H2O2 followed by heating for 20min at 120°C on a heating block. Next, the obtained slurry was sonicated in an autosampler cup, and finally, the slurry was introduced into a graphite tube and analyzed by the GFAAS with a Pb electrodeless discharge lamp (EDL). Calibration with aqueous standard solutions was used for Pb determination in food samples. The characteristic mass and limit of detection for Pb based on the integrated absorbance for a 2% (m/v) sample were 12±0.6pg and 0.003mgkg−1, respectively. The accuracy (95.1–102% recovery) and good precision (0.1–3.6%) of this procedure are illustrated by the results obtained for the 12 food reference materials. The proposed method is suitable for determination of trace Pb in solid food samples.

The roles of active species in photo-decomposition of organic compounds by microwave powered electrodeless discharge lamps

Knowledge of the effective radiation spectrum irradiating substrates from microwave powered electrodeless discharge lamps (MEDLs), and the active species that directly oxidize substrates in the photolytic process, is fragmentary and unclear. In this work, we conducted a comparative study using MEDLs made with quartz envelopes (MEDL-quartz) and with borosilicate Pyrex envelopes (MEDL-Pyrex) targeting the degradation of Rhodamine B (RhB) via radical-extinguishing tests. We found that UVC/UVB radiation is essential to generate •OH and H2O2 in the MEDL-quartz system. The degradation of RhB mostly originates from •OH species, which account for a contribution of 53.8%, while the remaining contribution is attributed to oxidation by H2O2 and direct photolysis. This degradation is influenced by several parameters. Acidic and neutral pHs, but not extreme alkaline pH, benefit the degradation. To ensure a high intensity of UVC/UVB, the optimum ratio of the MEDL volume to the aqueous solution volume (VL/VS) is 0.4. Concentrations of 0.15–0.20mmol/L of RhB are suitable to obtain an effective quantum absorbance in the MEDL-quartz system, showing a high decomposition rate of 5.6×10−3 (mmol/L)min−1. Moreover, two other substrates, Reactive Brilliant Red X-3B and Safranine T, were tested and found to be efficiently degraded in the MEDL-quartz system.

Flickering lamps

Many processes in electromagnetism vary with time. Some of them are well known, in particular those related to line frequencies of 50 Hz or 60 Hz such as fluctuating light output of discharge and incandescent lamps. The flickers of discharge and incandescent lamps have quite different physical principles involved, which are investigated experimentally using high-speed cameras and theoretically using simplified models. The topic is related to other phenomena such as the transient behaviour of phosphor layers covering the screen of oscilloscopes and the time-varying Lorentz force acting on the filament of light bulbs. All studies are well suited for teaching selected aspects of electromagnetism and light at undergraduate level at university.

The efficiency challenge of nitride light‐emitting diodes for lighting

We discuss the challenges of light‐emitting diodes in view of their application to solid‐state lighting. The requirement is to at least displace the quite efficient fluorescent, sodium, and high intensity discharge lamps used today in the main energy consuming lighting sectors, industrial, commercial and outdoors, with more efficient and better light quality lamps. We show that both from the point of view of cost of ownership and carbon emissions reduction, the relevant metric is efficiency, more than the cost of lumens. Then, progress from present performance requires identification of the loss mechanisms in light emission from LEDs, and solutions competing with mainstream c‐plane LEDS grown on sapphire need to be on par with these. Special attention is devoted to a discussion of the efficiency droop mechanisms, and of a recent direct measurement of Auger generated electrons which appear to be responsible for droop.

Solvent jet desorption capillary photoionization-mass spectrometry.

A new ambient mass spectrometry method, solvent jet desorption capillary photoionization (DCPI), is described. The method uses a solvent jet generated by a coaxial nebulizer operated at ambient conditions with nitrogen as nebulizer gas. The solvent jet is directed onto a sample surface, from which analytes are extracted into the solvent and ejected from the surface in secondary droplets formed in collisions between the jet and the sample surface. The secondary droplets are directed into the heated capillary photoionization (CPI) device, where the droplets are vaporized and the gaseous analytes are ionized by 10 eV photons generated by a vacuum ultraviolet (VUV) krypton discharge lamp. As the CPI device is directly connected to the extended capillary inlet of the MS, high ion transfer efficiency to the vacuum of MS is achieved. The solvent jet DCPI provides several advantages: high sensitivity for nonpolar and polar compounds with limit of detection down to low fmol levels, capability of analyzing small and large molecules, and good spatial resolution (250 μm). Two ionization mechanisms are involved in DCPI: atmospheric pressure photoionization, capable of ionizing polar and nonpolar compounds, and solvent assisted inlet ionization capable of ionizing larger molecules like peptides. The feasibility of DCPI was successfully tested in the analysis of polar and nonpolar compounds in sage leaves and chili pepper.

Hybrid Switched-Inductor Converters for High Step-Up Conversion

In applications where the high voltage gain is required, such as photovoltaic grid-connected system, fuel-cell and high-intensity discharge lamps for automobile, high step-up dc-dc converters have been introduced to boost the low voltage to a high bus voltage. The voltage gain of traditional boost converter is limited, considering the issues such as the system efficiency and current ripple. This paper proposes a class of hybrid switched-inductor converters (H-SLCs) for high step-up voltage gain conversion. First, the topological derivation of H-SLCs is deduced by combining the passive and active switched-inductor unit; second, this paper illustrates the operation modes of the proposed asymmetrical and symmetrical converters; third, the performance of the proposed converters is analyzed in detail and compared with existing converters; finally, a prototype is established in the laboratory, and the experimental results are given to verify the correctness of the analysis.

A High Gain Input-Parallel Output-Series DC/DC Converter With Dual Coupled Inductors

High voltage gain dc-dc converters are required in many industrial applications such as photovoltaic and fuel cell energy systems, high-intensity discharge lamp (HID), dc back-up energy systems, and electric vehicles. This paper presents a novel input-parallel output-series boost converter with dual coupled inductors and a voltage multiplier module. On the one hand, the primary windings of two coupled inductors are connected in parallel to share the input current and reduce the current ripple at the input. On the other hand, the proposed converter inherits the merits of interleaved series-connected output capacitors for high voltage gain, low output voltage ripple, and low switch voltage stress. Moreover, the secondary sides of two coupled inductors are connected in series to a regenerative capacitor by a diode for extending the voltage gain and balancing the primary-parallel currents. In addition, the active switches are turned on at zero current and the reverse recovery problem of diodes is alleviated by reasonable leakage inductances of the coupled inductors. Besides, the energy of leakage inductances can be recycled. A prototype circuit rated 500-W output power is implemented in the laboratory, and the experimental results shows satisfactory agreement with the theoretical analysis.

Optimizing parameters for a dynamic model of high-frequency HID lamps using genetic algorithms

This work is carried out to optimize the basic parameters of a dynamic model of high-frequency high intensity discharge lamps, which includes the effect of the phenomenon of acoustic resonance on the electrical parameters of the lamps. Hybrid modeling techniques are used, taking as their starting point the energy balance equations inside the lamp. The optimization of parameters is carried out using techniques based on genetic algorithms, included in the global optimization toolbox of Matlab. The implementation of the model is performed in Matlab R2011a. The result is a dynamic model for HID lamps at high frequency, validated for a high-pressure sodium lamp.

Testing New Lighting Technology in a Park Pedestrian Area

European Union directives on ecodesign requirements of discharge lamps have also their effect on street lighting. The commonly used mercury vapor lamps have to be replaced starting from 2015. Pori, a middle sized city situated on the west coast of Finland, has about 17 000 mercury discharge lamps for street lighting. This was the starting point for Pori Energia, the utility that takes care of public lighting in the city of Pori, and for Satakunta University of Applied Sciences (SUAS) to initiate an investigation of alternative lamps. This paper considers the results of a practical experiment of four lamp types applicable for street lighting: high pressure sodium lamp, metal halide lamp, inductive lamp and led lamp. The lamps were installed above a park pedestrian area and the illumination was measured in various circumstances in the winter. In addition, electric measurements were carried out in the Electric Laboratory of SUAS. Also a small scale opinion poll among the pedestrian area users was included in the research. The results show that the luminous flux of all of the new lamp types was higher than that of the old mercury lamps. This was clearly proved even when the aging factor was taken into account. The led lamp seems to be the best choice relative to illumination/power consumption ratio. The park pedestrian area users were also satisfied with the chromatic tone of the white led light. However, the led lamp technology is not in mature phase and using it widely may cause extraordinary costs in the infrastructure of electric networks.

Quality Control Methods of Al<sub>2</sub>O<sub>3</sub> Based Ceramic Injection Molding Raw Materials

In the illuminant industry, for producing arc tube parts for high intensity discharge lamps the applied method is the ceramic injection molding. The ceramic arc tube parts are made of high purity alumina powder. By producing ceramic parts, one of the most critical step is to optimizing the injection molding process, [1] but first of all we need to know the properties of injection molding raw material, because later the molding process will be optimized for this material, to decrease the amount of cracked ceramics.For producing ceramic arc tube parts (plugs), there are used two different major components for producing injection molding raw material (feedstock): high purity alumina powder as the main component, and an organic paraffin wax as a binder material. It is expressly important to know the material, physical and chemical properties of these components, since mainly these have affect on the homogenity of feedstock, and therefore on the quality of end product. [3]In this research, both of the main components and the moldable raw material was investigated by visual, physical, chemical and thermal methods. As most important and main statement, the researchers found that the dynamic viscosity of the injection molding raw material depends on the used mixer equipment and the applied deformation velocity.Applied analitycal methods were laser granulometry, differential thermal analysis, and rheological analysis.

Automatic Street Lighting System Uses NE555 Integrated Circuit and LDR

Street light is a raised source of light that is commonly used along walkways and streets when the surrounding turns dark. Presently High Intensity Discharge lamps are used for street lighting system based on principle of gas discharge, but they consume more power and have low CRI. By replacing the HPS with LED lamps we can save a lot of energy, reduce Co2 emissions and using the autoswitching system we can also control power consumptions at the streets and eliminating manpower. With the broad availability of flexlighting technology like light-emitting diode Lamps, the street lighting system is fast reacting, reliably operating, and less power-conserving become reality. This project is all about to eliminate the manpower and reduce the energy consumptions at the street lights. This project includes controlling a circuit of street lights with the help of Transformer, Rectifier, Filter unit, LDR, NE 555 IC,BC 547 transistor, SPDT Relay, LED Lamp, resistance and capacitor during day and night.

Studies on laser-assisted Penning ionization by the optogalvanic effect in Ne/Eu hollow cathode discharge

Laser-assisted Penning ionization (LAPI) is detected in a Ne/Eu hollow cathode (HC) discharge lamp using the pulsed optogalvanic (OG) method. In the Ne/Eu discharge, doubly ionized europium excited energy levels Eu[4f(7)(P(7/2,5/2)6)] lie within the thermal limit (∼kT) from the laser-excited neon's energy level [2p(5)(P3/202)3p or 2p(8) (in Paschen notation)] lying at 149,848 cm(-1). Therefore, Penning ionization (PI) of europium atoms likely to occur into its highly excited ionic states is investigated. To probe the PI of europium, the temporal profiles of its counterpart neon OG signal are studied as a function of discharge current for the transitions (1s(4)→2p(8)) and (1s(2)→2p(2)), corresponding to 650.65 and 659.89 nm wavelengths, respectively. It is observed that PI of europium alters the overall discharge characteristics significantly and, hence, modifies the temporal profile of the OG signals accordingly. The quasi-resonant ionizing energy transfer collisions between laser-excited Ne 2p(8) atoms and electronically excited europium P(9/2)10 atoms are used to explain the LAPI mechanism. Such LAPI studies carried out in HC discharge could be useful for the discharge of a metal-vapor laser with appropriate Penning mixtures.

Spectral and photopic studies for high intensity discharge (HID) lamps

Outdoor lighting sources such as High Intensity Discharge lamps (HID) are common in these days. This research is focusing on the relation between the spectral power distribution and luminous efficiency function V (λ ), which describes the average spectral sensitivity of human visual perception of brightness. The most useable HID lamps inside Egyptian markets are high pressure mercury (HPM), high pressure sodium (HPS) and metal halide (MH). A set up based on single monochromator and integrating sphere for relative spectral power distribution and absolute luminous flux measurements are used, respectively. The accompanied standard uncertainties with the measurements are evaluated.

The Photometric Properties of Microwave High Intensity Discharge (HID) Lamps

The Photometric Properties of Microwave High Intensity Discharge (HID) Lamps

System for Synchronous Detection Trace of Explosives and Drags Substances on Human Fingers

The sampling unit of the device, based on ion mobility spectroscopy technique, for detection of ultra small (trace) substances concentration on human fingers and documents is described. The vapor pressure of many dangerous substances is very small; so the heating of an investigated surface is needed for effective detection. However the direct heating of the human fingers by irradiation of the gas-discharge lamp is not effective because a small concentration of the melamine (pigment of the black or brown color) in the skin of the human palm. Therefore in this work the combination of the two methods is used: a grid is heated by the irradiation of the gas-discharge lamp and a grid heats the surface of the finger which is pressed to a grid.

Spectroscopic measurements of plasma temperatures and electron number density in a uranium hollow cathode discharge lamp

The plasma parameters including neutral species temperature, atomic excitation temperature and electron number density in a see-through type, homemade uranium hollow cathode discharge lamp with neon as a buffer gas have been investigated using optical emission spectroscopic techniques. The neutral species temperature has been measured using the Doppler broadening of a neon atomic spectral line. The atomic excitation temperature has been measured using the Boltzmann plot method utilizing uranium atomic spectral lines. The electron number density has been determined from the Saha-Boltzmann equation utilizing uranium atomic and ionic spectral lines. To the best of our knowledge, all these three plasma parameters are simultaneously measured for the first time in a uranium hollow cathode discharge lamp.

Plan de Mejoramiento del Alumbrado Público de las Principales Avenidas de la Ciudad de Quito Mediante la Sustitución por Lámparas de Inducción

El alumbrado vial, es una necesidad básica de la población, su evolución marca hitos en el desarrollo de nuevas tecnologías. Este artículo se centra en la investigación y análisis comparativo del comportamiento de las lámparas actualmente utilizadas en el alumbrado público de la ciudad de Quito, referidos a los parámetros más importantes de: calidad de iluminación, eficiencia energética e impacto ambiental, para establecer su potencial de mejoramiento, alineado con estándares vigentes en normas internacionales y regulaciones nacionales. Se propone el uso de lámparas de inducción con controles básicos y lámparas de inducción con controles inteligentes, en comparación a las lámparas de descarga actualmente utilizadas. Se desarrollan tres posibles escenarios de análisis: antes, durante y después de la implementación de un proyecto con lámparas de inducción, donde se estiman los beneficios de las mismas: disminución del costo de operación y mantenimiento, reducción del consumo de energía eléctrica, protección del ambiente en varias escalas y la directa influencia en la preservación de la salud, seguridad e integridad de las personas.

ISCEV Standard for full-field clinical electroretinography (2015 update).

This document, from the International Society for Clinical Electrophysiology of Vision (ISCEV), presents an updated and revised ISCEV Standard for full-field clinical electroretinography (ffERG or simply ERG). The parameters for Standard flash stimuli have been revised to accommodate a variety of light sources including gas discharge lamps and light emitting diodes. This ISCEV Standard for clinical ERGs specifies six responses based on the adaptation state of the eye and the flash strength: (1) Dark-adapted 0.01 ERG (rod ERG); (2) Dark-adapted 3 ERG (combined rod-cone standard flash ERG); (3) Dark-adapted 3 oscillatory potentials; (4) Dark-adapted 10 ERG (strong flash ERG); (5) Light-adapted 3 ERG (standard flash "cone" ERG); and (6) Light-adapted 30 Hz flicker ERG. ISCEV encourages the use of additional ERG protocols for testing beyond this minimum standard for clinical ERGs.

Investigating antennas as ignition aid for automotive HID lamps

This paper considers the ignition of mercury-free high-intensity discharge (HID) lamps for car headlights. Due to safety reasons, these lamps need to have a fast run-up phase which is ensured, amongst other things, by a high Xe pressure of roughly 15 bar (cold) in the discharge vessel. The high Xe pressure causes an increased ignition voltage compared with former mercury-containing automotive HID lamps or low-pressure lamps used for general-lighting applications.The increase in ignition voltage can be limited if the electric field in front of the electrodes is raised by an uplifting of the electrical conductivity along the outer wall of the inner bulb either by a conductive layer on its surface or by a dielectric barrier discharge (DBD) within the outer bulb. This paper considers on the one hand conventional antennas deposited by physical vapour deposition (PVD) and on the other hand a combination of these antennas with a DBD within the outer-bulb operated in 100 mbar Ar as ignition aids. In both cases the antenna potential and antenna width are varied. Additionally, the effects of antenna thickness and antenna material are investigated.The ignition voltage, ignition current and light emission during ignition are measured on a nanosecond timescale. Furthermore, for the very first time, the ignition process is recorded in four consecutive intensified charge-coupled device images using a high-speed camera system with a time resolution in the range of nanoseconds.It was found that antennas strongly reduce the ignition voltage of automotive HID lamps. Active antennas reduce the ignition voltage significantly more than passive antennas, proportional to the conductance of the antenna. Combining conventional antennas with an outer-bulb discharge reduces the ignition voltage from 19 kV without any ignition aid to the intrinsic ignition voltage of the lamp below 10 kV, in the best case.

Arc Shape of High-Intensity Discharge Lamps: Simulation and Experiments

A stationary compressible three-dimensional (3D) model of photothermal processes inside an arc tube of a high-intensity discharge lamp is developed on the basis of the finite element method. It takes plasma, electrodes, and the tube wall into account and enables simulation of acoustic phenomena. The temperature profile of the discharge arc is used as a marker for the emission of visible light. Complementary, experimental investigations are conducted at different modulation frequencies. A photodetector array is used to record 2D information about the light intensity distribution. The shape and length of the discharge arc are determined and compared to numerical results.