Discharge Lamps Research Articles

Light-emitting Diodes and the Modulation of Specialty Crops: Light Sensing and Signaling Networks in Plants

The technology to drive the output of individual arrays of light-emitting diodes (LEDs) on timescales down to microseconds is enabling plant scientists and growers control over irradiance- and spectrum-induced plant responses. The two light sensing and signaling networks that regulate desired plant responses involve either photoreceptors (PR) and/or photosynthesis (PSN). These networks control morphological, physiological, and developmental processes (e.g., seed development and germination, seedling development, apical meristem formation, differentiation, flowering, etc.) as well as the energy distribution within the plant. Understanding the individual plant responses and the synergy between the PR and PSN networks will assist in the selection and timing of LED light programs for crop regulation and growth. Both networks sense and respond to irradiance and narrow-band spectra between 350 and 750 nm although their modes of action are different. Comparing the PR and PSN networks and their effect on plants shows that the PR network primarily regulates developmental processes in new tissues while the PSN network regulates routine operational processes. The two networks are required for healthy plant growth and are reliant on each other for biological fitness. A balance between these two networks will result in greater plant efficacy and can be achieved by light programs whose irradiance, spectra, duration, and timing can be regulated. Replacing high-intensity discharge (HID) lamps with LEDs is a catalyst for a fundamental change in plant lighting and we are on a steep learning curve to fully realize how to fully control LED technology in plant growth applications.

Commercial Transition to LEDs: A Pathway to High-value Products

The use of light-emitting diodes (LEDs) to support plant growth is a radical departure from use of gas-discharge lamps, which were developed in mid-19th and widely adopted by the industry during the 20th century. Initial investigation by the National Aeronautics and Space Administration (NASA) in the late 1980s on the use of LEDs to grow plant in space is resulting in an industry-wide transition from gas discharge to solid-state lighting systems. This global transformation is given urgency by national policies to reduce energy consumption and being facilitated by ready access to information on LEDs. The combination of research, government policy, and information technology has resulted in an exponential increase in research into the use and application of LED technology in horticulture. Commercial horticulture has identified the opportunities provided by LEDs to optimize light spectra to promote growth, regulate morphology, increase nutrient content, and reduce operating costs. LED-light technology is enabling the development of innovative lighting systems, and is being incorporated into large-scale plant factories for the production of edible, ornamental, and medicinal plants. An overview of prevalence of readily accessible information on LEDs and implications for future adoption in horticulture is discussed.

Total pressure and atomic ratio effect on transport coefficients of HgTlI discharge plasma using a LTE chemical model

The aim of this paper is the study of the effect of total pressure and mercury to thallium atomic ratio on transports coefficients such as thermal conductivity, viscosity and electric conductivity of a HgTlI discharge lamp. For this, a chemical model under Local Thermodynamic Equilibrium conditions has been developed to compute the plasma composition and transports coefficients using the theoretical approach of Chapman completed by the work of Enskog, Hirschfelder and Devoto. It has been shown that the variation of the two parameters has a significant effect on the transport coefficients.

Pulsed Voltage-Mode Supply for High-Pressure Sodium Lamps

This paper presents the current stabilization technique that uses high-frequency voltage pulses to supply discharge lamps and takes advantage of the resistivity of the plasma to limit the current through the lamp. A computational model that regards the chemical and physical discharge characteristics for high-pressure sodium lamp was implemented in MATLAB to validate the proposed power supply. A 150-W prototype was implemented to confirm the current stabilization technique.

Analysis of Active-Network Converter With Coupled Inductors

High step-up voltage gain dc-dc converters are widely applied in fuel cell stacks, photovoltaic arrays, battery sources, and high intensity discharge lamps power systems. Active-network converters with coupled inductors (CL-ANC) are derived from switched inductor active-network converters (SL-ANC). The proposed converter contains two coupled inductors which can be integrated into one magnetic core and two power switches. The converter can provide a relatively high voltage conversion ratio with a small duty cycle; the voltage and current stress of power switches are low which is helpful to reduce the losses. This paper shows the key waveforms of the CL-ANC and detailed derivation of the steady-state operation principle. The voltage conversion ratio and the effect of the leakage inductance on voltage gain are discussed. The voltage stress and current stress on the power devices are illustrated and the comparison between the proposed converter and SL-ANC are given. Finally, the prototype has been established in the lab with 200 V and 400 V output under different turn ratios. Experimental results are given to verify the correctness of the analysis.

Ultrasonic nebulization extraction/low pressure photoionization mass spectrometry for direct analysis of chemicals in matrices

A novel ultrasonic nebulization extraction/low-pressure photoionization (UNE-LPPI) system has been designed and employed for the rapid mass spectrometric analysis of chemicals in matrices. An ultrasonic nebulizer was used to extract the chemicals in solid sample and nebulize the solvent in the nebulization cell. Aerosols formed by ultrasonic were evaporated by passing through a transferring tube, and desolvated chemicals were ionized by the emitted light (10.6 eV) from a Krypton discharge lamp at low pressure (∼68 Pa). First, a series of semi/non-volatile compounds with different polarities, such as polycyclic aromatic hydrocarbons (PAHs), amino acids, dipeptides, drugs, nucleic acids, alkaloids, and steroids were used to test the system. Then, the quantification capability of UNE-LPPI was checked with: 1) pure chemicals, such as 9,10-phenanthrenequinone and 1,4-naphthoquinone dissolved in solvent; 2) soil powder spiked with different amounts of phenanthrene and pyrene. For pure chemicals, the correlation coefficient (R2) for the standard curve of 9,10-phenanthrenequinone in the range of 3 ng–20 μg mL−1 was 0.9922, and the measured limits of detection (LOD) was 1 ng ml−1. In the case of soil powder, linear relationships for phenanthrene and pyrene from 10 to 400 ng mg−1 were obtained with correlation coefficients of 0.9889 and 0.9893, respectively. At last, the feasibility of UNE-LPPI for the detection of chemicals in real matrices such as tablets and biological tissues (tea, Citrus aurantium peel and sage (Salvia officinalis) leaf) were successfully demonstrated.

Water Purification by a Lamp Discharge-Electronic Ballast System Using a Full Bridge Inverter

The presence of pathogenic microorganisms in the water poses a risk to the health of consumers of all ages. Water conventional chemical treatments are not always a good solution. Difficult to implement, they have the double disadvantage of denaturing the organoleptic qualities of water: by acting on its physico-chemical composition and rejection of polluted water. Chlorination treatment is generally used to solve the bacteriological quality problems of both unconventional drinking water and treated wastewater. The use of chlorination is increasingly avoided due to the production of chlorinated products of carcinogenic and to the little action on the virus. The search for alternative solutions has summarized in several studies. The use of “ultraviolet irradiation” is still interesting alternative solution. Sterilization system using UV radiation is recommended in health services, hospitals, pharmacies, agriculture, aquariums, water extraction fromwells orrainwater, etc. UV radiationhas a fast acting, efficient, safe and constitutes an economic process that respects the environment. In recent years, high-frequency electronic ballasts for discharge lamps have been presented as a substitute for the magnetic ballast. because of their superior qualities such as high system performance (improved power factor), weight light, the light produced per watt, long service life, the function of lighting control, non-flashing, non-presence of audible noise and more technical aspects and requirements, special attention must be given to costs of an electronic ballast. This paper presents the design of a high frequency current power supply (electronic ballast based PWM inverter) to power a low-pressure UV lamp Mercury-Argon which has a germicidal effect for water treatment. So, the main purpose is to generate maximum UV at 253.7nm (germicidal effect) and this is achieved by having at the ballast output a sinusoidal current with a frequency of 50 KHz and rms value of 0.65 A.

Microwave-assisted ultraviolet digestion of petroleum coke for the simultaneous determination of nickel, vanadium and sulfur by ICP-OES

A method for the simultaneous determination of Ni, V and S in petroleum coke by inductively coupled plasma optical emission spectrometry (ICP-OES) after microwave-assisted ultraviolet digestion (MW-UV) in closed vessels was proposed. Digestion was performed using electrodeless discharge lamps positioned inside quartz vessels and turned on by microwave radiation. The following parameters were evaluated: HNO3 concentration (15mL of 1, 4, 7, 10 or 14.4molL−1), volume of H2O2 (30%, 1 or 3mL), sample mass (100, 250 or 500mg) and heating time (40 or 60min) with or without the use of UV lamps. Digestion efficiency was evaluated by the determination of the residual carbon content (RCC) in digests. Using UV lamps lower RCC was obtained and the combination of 4molL−1 HNO3 with 3mL of H2O2 and 60min of heating allowed a suitable digestion of up to 500mg of petroleum coke (RCC< 21%). The agreement with the reference values for Ni, V and S (obtained by digestion of petroleum coke by microwave-induced combustion) and with a certified reference material of petroleum coke was between 96 and 101%. The proposed method was considered as advantageous when compared to American Society for Testing and Materials method because it allowed the simultaneous determination of Ni, V and S with lower limit of detection (0.22, 0.12 and 8.7µgg−1 for Ni, V and S, respectively) avoiding the use of concentrated nitric acid and providing digests suitable for routine analysis by ICP-OES.

Extended producer responsibility for lamps in Nordic countries: best practices and challenges in closing material loops

Extended Producer Responsibility (EPR) schemes are adopted not only to promote collection and recycling of waste products but also to close material loops and incentivise ecodesign. These outcomes are also part of creating a more circular economy. Evaluations of best practices can inform how to further optimise systems towards more ambitious collection, recycling and recovery of both hazardous and critical materials. Gas discharge lamps in particular are a key product category in this regard, considering both the presence of mercury and of rare earth materials in this waste stream. Nordic countries in particular are known for advanced collection and recycling systems and this article compares the EPR systems for gas discharge lamps. The EPR systems for lamps are evaluated using theory-based evaluation approaches to analyse both the performance of lamp EPR systems and challenges perceived by key stakeholders. The cases were constructed based on primary and secondary literature, statistical data, and interviews with stakeholders. The findings indicate that the collection and recycling performance is generally still high for gas discharge lamps in the Nordic countries, despite some differences in approach and structure of the EPR systems, but there remain opportunities for further improvement. In terms of EPR goals, there is evidence of improved waste management of these products as a result of the systems; however, there also remain significant challenges, particularly in terms of ecodesign incentives. The key factors for best practice are discussed, including aspects of the rule base, infrastructure, and operations. The particular characteristics of this waste category, including the rapidly changing technology, also pose challenges for EPR systems in the future.

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.

An Efficient High Gain DC-DC Converter for Automotive Applications

This paper presents a high gain DC-DC converter which uses a clamp circuit to achieve soft switching. The proposed converter is designed to supply a high intensity discharge (HID) lamp used in automobile head lamps. The converter operates from a 12V input supply and provides an output voltage of 120V at 35W output power. A clamp circuit consisting of a clamp capacitor, clamp switch and resonant inductor will help to achieve zero voltage switching (ZVS) of the both main and clamp switches. The practical performance of the converter was validated through experimental results. Results obtained from the prototype hardware prove that the converter meets the requirements of HID lamp application and can be a very good alternative to existing converters.

Population Distribution of Excited States in Cs Electrodeless Discharge Lamp**Supported by the National Natural Science Foundation of China under Grant Nos 11074011 and 91436210.

We measure the intensity of fluorescence spectral lines of Cs atoms in an electrodeless discharge lamp from visible light to the near-infrared region of 400–1000 nm. To build an excited state Faraday anomalous dispersion optical filter, the population ratios between the excited states are calculated by rate equations and the spontaneous transition probabilities. The electrodeless discharge lamp with populations in the excited states can be used to realize the frequency stabilization reference for lasers at multiwavelength and the excited state Faraday anomalous dispersion optical filter for submarine communication applications in blue—green wavelengths to simplify the system.

Ultra-high purity tungsten and its applications

High purity (>99.999wt.%, 5N) or ultra-high purity (>99.9999wt.%, 6N) tungsten (W) electrodes are vital to the performance and lifetime of high intensity discharge (HID) lamps. On the other hand, alloys based on high purity (>99.99wt.% or 99.995wt.%, 4N or 4N5) W are used as sputtering targets to deposit the films in semiconductor devices. In this study, a highly efficient and cost-saving method for mass producing 6N W powder has been developed. The 5N and 6N W rods and wires for the electrodes of HID lamps have been manufactured by using this powder. In addition, vacuum hot pressing has been employed to prepare 4N5 tungsten–titanium (W–Ti) and 4N tungsten–silicon (W–Si) sputtering targets successfully. The impurities and microstructures of the developed high purity W products have been investigated and are suitable for lighting, semiconductor and photovoltaic applications.

On the Conductance of the Gas Discharge Plasma at Space Anisotropic Excitation

AbstractThe galvanic manifestation of two transformations of degenerate magnetic states of the neon atom, namely self‐alignment → non‐alignment and alignment ↔ orientation is studied by monitoring the voltage across the discharge in a range of hollow cathode discharge (HCD) lamps. The application of a magnetic field to the discharge disorders the self‐alignment. Alignment and orientation are optically induced and their effect on the discharge conductance is compared by measuring the optogalvanic signals. The degenerate states investigated are found to contribute to the gas discharge conductance in a manner which depends on their degree of coherence. Various hollow cathode discharge media are studied including Ne/As, Ne/Cu, Ne/Ni, Ne/Cd, Ne/Li and Ne/Ca in the corresponding trademarked HCD spectral lamps. (© 2015 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Numerical investigation of symmetry breaking and critical behavior of the acoustic streaming field in high-intensity discharge lamps

For energy efficiency and material cost reduction it is preferred to drive high-intensity discharge lamps at frequencies of approximately 300 kHz. However, operating lamps at these high frequencies bears the risk of stimulating acoustic resonances inside the arc tube, which can result in low frequency light flicker and even lamp destruction. The acoustic streaming effect has been identified as the link between high frequency resonances and low frequency flicker. A highly coupled three-dimensional multiphysics model has been set up to calculate the acoustic streaming velocity field inside the arc tube of high-intensity discharge lamps. It has been found that the velocity field suffers a phase transition to an asymmetrical state at a critical acoustic streaming force. In certain respects the system behaves similar to a ferromagnet near the Curie point. It is discussed how the model allows to investigate the light flicker phenomenon. Concerning computer resources the procedure is considerably less demanding than a direct approach with a transient model.

HID lamps fed by a non conventional pulsed current

The main purpose of the present work consists in the study of the influence of electronic power supply of high intensity discharge (HID) lamp by square wave form with variable short current drop and the effects on the mercury lamp properties. The acquisition of the arc current and arc voltage enables us to investigate the influence of this power supply on the electrical characterization such as the behavior of the lamp conductance. A comparison between simulations and measurements of HID lamps confirms the agreement between the electric model and the experiment.

Characterization of Discharge Arc Flicker in High-Intensity Discharge Lamps

High-intensity discharge lamps frequently suffer emission disturbances due to the excitation of acoustic resonances. This paper presents experimentally determined light flicker frequencies and arc motion frequencies at different excitation frequencies and modulation depths. Light intensity fluctuation has been detected with a photodiode. Simultaneously, arc motion was recorded with a camera. The frequencies of both methods are in very good agreement. The behavior of the flicker frequency and the arc motion frequency changes significantly near the acoustic eigenfrequency.

Bulk superconducting gap of V3Si studied by low-energy ultrahigh-resolution photoemission spectroscopy

We have performed low-energy ultrahigh-resolution photoemission spectroscopy (PES) of A15 compound V3Si with a xenon-plasma discharge lamp to elucidate the bulk superconducting gap. Below the superconducting transition temperature (Tc=15.9K), we found a sharp quasiparticle peak at the Fermi level in the PES spectrum. The gap spectrum is well fitted by a single s-wave superconducting-gap function together with a dip structure at ∼30meV suggestive of a strong electron-phonon coupling. The anomalous in-gap state previously observed in the PES measurement with high-energy photons is absent or negligibly small in the present bulk-sensitive measurement. The present PES result shows that V3Si is a single-gap s-wave superconductor.

Plant developmental consequences of lighting from above or below in the production of Poinsettia

Summary Artificial light is used for many horticultural crops produced in greenhouses, not least ornamental pot plants. New technologies such as LEDs will possibly replace high intensity discharge lamps as the main technology for lighting in horticulture. However, LEDs are quite different from discharge lamps as regards the handling of waste heat. They have low output of radiant heat, but the waste heat is produced in the fixture and must be cooled away using fans or heat sinks. The low radiant heat will result in lower leaf temperature in the crop, possibly prolonging production time. LED fixtures are often voluminous due to the need for cooling systems, creating large shade effects when installed at the top of the greenhouse. To overcome these issues, this greenhouse study tested placing the light source, in the form of LED bars, under the crop, thus illuminating the abaxial side of the leaves. The results showed that the growth and elongation of the Euphorbia plants was similar irrespective of whether the light was supplied at the abaxial or adaxial side of the leaves. The air temperature within the canopy increased when the light source was placed within the canopy and fresh weight, dry weight and bract length of the bract also increased compared with when the same light was supplied from above, probably due to the higher temperature. Placing LED light sources below the canopy of potted ornamentals was found to be a feasible solution for supplying supplementary light.

Micro-structured electron accelerator for the mobile gas ionization sensor technology

Abstract. Mobile and economically priced gas monitoring and warning systems will become increasingly important for civil security, such as in fire brigade operations in undefined hazardous environments (Daum et al., 2006). Normally, photoionization detectors (PIDs) are used for the detection of gases. Hereby, the principle is based upon the ionization of the measured gas by photons, which are generated by a high-energetic gas discharge lamp with energy of 10–11 eV. Besides the detrimental unspecific gas detection because of the ionization of all gases with ionization potential (IP) below the provided photon energy, sensors also have a short lifetime combined with a high cost (http://www.intlsensor.com/pdf/photoionization.pdf). This can be remedied by the concept of an electronic supported photoionization detector (ePID; Zimmer et al., 2012) consisting of a durable UV-LED with an above-positioned electron accelerator chip manufactured on a glass substrate by planar technology. Photoelectrons are extracted by UV illumination out of the bottom electrode and will be accelerated to an energy matching the ionization potential of the gas by a downstream acceleration grid. Thereby, the stable honeycomb-structured grid acts as a porous separator between the evacuated electron acceleration path due to nm scaling and the ionization area of the detector. To enhance the emitting area yielding a higher photoelectron current, the grid structure almost levitates, realized by the use of compatible planar technological processes such as reactive ion etching (RIE) and isotropic wet etching of sacrificial layers, which will be explained in detail in this paper. Furthermore, the tunability of the grid's acceleration voltage would enable a substance-specific determination of the gas composition, where the ionization of the analytes is clearly performed by photoelectrons instead of photons.